Sex differences in human physiology#Muscle mass and strength

File:YChromShowingSRY2.png showing the SRY gene. SRY is a gene which regulates sexual differentiation.]]

{{See also|Sexual differentiation in humans}}

The human genome consists of two copies of each of 23 chromosomes (a total of 46).{{cite book|last1=Mills |first1=Melinda C. |last2=Barban |first2=Nicola |last3=Tropf |first3=Felix C. |title=An Introduction to Statistical Genetic Data Analysis |date=2020 |publisher=MIT Press |isbn=978-0262357449 |page=9 |url=https://books.google.com/books?id=zrDMDwAAQBAJ&pg=PA9}} One set of 23 comes from the mother and one set comes from the father. Of these 23 pairs of chromosomes, 22 are autosomes, and one is a sex chromosome. There are two kinds of sex chromosomes–X and Y. In humans and in almost all other mammals, females carry two X chromosomes, designated XX, and males carry one X and one Y, designated XY.

A human egg contains only one set of chromosomes (23) and is a haploid. Sperm also have only one set of 23 chromosomes and are therefore haploid. When an egg and sperm fuse at fertilization, the two sets of chromosomes come together to form a unique diploid individual with 46 chromosomes.{{cite book|last1=Solomon |first1=Eldra |last2=Martin |first2=Charles |last3=Martin |first3=Diana W. |last4=Berg |first4=Linda R. |title=Biology |date=2014 |publisher=Cengage Learning |isbn=978-1305179899 |pages=218, 240 |url=https://books.google.com/books?id=Z0rAAgAAQBAJ&pg=PT252}}

The sex chromosome in a human egg is always an X chromosome since a female only has X sex chromosomes. In sperm, about half the sperm have an X chromosome and half have a Y chromosome. If an egg fuses with sperm with a Y chromosome, the resulting individual is male. If an egg fuses with sperm with an X chromosome, the resulting individual is female. There are rare exceptions to this rule in which, for example, XX individuals develop as males or XY individuals develop as females.{{cite book|last1=Snustad |first1=D. Peter |last2=Simmons |first2=Michael J. |title=Principles of Genetics |date=2015 |publisher=John Wiley & Sons |isbn=978-1119142287 |page=100 |url=https://books.google.com/books?id=NBB0CgAAQBAJ&pg=PA100}} There are other variations of sex chromosomes that lead to a variety of different physical expressions.{{cite book|last1=Rieger |first1=Rigomar |last2=Michaelis |first2=Arnd |last3=Green |first3=Melvin M. |title=Glossary of Genetics: Classical and Molecular |date=2012 |publisher=Springer Science & Business Media |isbn=978-3642753336 |page=449 |url=https://books.google.com/books?id=5azxCAAAQBAJ&pg=PA449}}

The X-chromosome carries a larger number of genes in comparison to the Y-chromosome. In humans, X-chromosome inactivation enables males and females to have an equal expression of the genes on the X-chromosome since females have two X-chromosomes while males have a single X and a Y chromosome. X-chromosome inactivation is random in the somatic cells of the body as either the maternal or paternal X-chromosome can become inactivated in each cell. Thus, females are genetic mosaics.{{cite journal |vauthors=Carrel L, Willard HF |title=X-inactivation profile reveals extensive variability in X-linked gene expression in females |journal=Nature |volume=434 |issue=7031 |pages=400–404 |date=March 2005 |pmid=15772666 |doi=10.1038/nature03479 |bibcode=2005Natur.434..400C |s2cid=4358447}}

{{See also|Secondary sex characteristics|Human body shape|Female body shape}}

• Externally, the most sexually dimorphic portions of the human body are the chest, the lower half of the face, and the area between the waist and the knees.{{cite book|url=https://www.bartleby.com/107/index.html |title=Gray's Anatomy of the Human Body |first=Henry |last=Gray |date=1918 |asin=B000TW11G6 |publisher=Lea & Febiger |edition=20th}}
• Males weigh more than females on average.{{cite book|last1=Robert-McComb |first1=Jacalyn |last2=Norman |first2=Reid L.|last3= Zumwalt |first3=Mimi |title=The Active Female: Health Issues Throughout the Lifespan |date=2014 |publisher=Springer Science+Business Media |isbn=978-1461488842 |pages=223–238 |url=https://books.google.com/books?id=mUjABAAAQBAJ&pg=PA223}}
• On average, males are taller than females by about 7% (12 cm).{{cite web |last1=Roser |first1=Max |last2=Appel |first2=Cameron |last3=Ritchie |first3=Hannah |title=Human Height |url=https://ourworldindata.org/human-height |website=Our World in Data |access-date=12 February 2025 |language=en |date=1 May 2021}}{{cite journal |author1=NCD Risk Factor Collaboration |title=A century of trends in adult human height |journal=eLife |date=26 July 2016 |volume=5 |doi=10.7554/eLife.13410|doi-access=free |pmid=27458798 |hdl=10044/1/33599 |hdl-access=free |pmc=4961475 }}
• On average, males have a larger waist in comparison to their hips (see waist–hip ratio) than females.{{Cite journal |last=Kościński |first=Krzysztof |date=2014 |title=Assessment of Waist-to-Hip Ratio Attractiveness in Women: An Anthropometric Analysis of Digital Silhouettes |journal=Archives of Sexual Behavior |volume=43 |issue=5 |pages=989–997 |doi=10.1007/s10508-013-0166-1 |issn=0004-0002 |pmc=4050298 |pmid=23975738}}{{Cite journal |last1=Stevens |first1=J |last2=Katz |first2=EG |last3=Huxley |first3=RR |date=2010 |title=Associations between gender, age and waist circumference |journal=European Journal of Clinical Nutrition |volume=64 |issue=1 |pages=6–15 |doi=10.1038/ejcn.2009.101 |issn=0954-3007 |pmc=5909719 |pmid=19738633}}
• In females, the index and ring fingers tend to be either more similar in size or their index finger is slightly longer than their ring finger, whereas male's ring finger tends to be longer.{{cite book|last=Halpern |first=Diane F. |title=Sex Differences in Cognitive Abilities: 4th Edition |date=2013 |publisher=Psychology Press |isbn=978-1136722837 |page=188 |url=https://books.google.com/books?id=ocl5AgAAQBAJ&pg=PA188}}

{{multiple image

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| footer = Comparison between a male (left) and a female pelvis (right).

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The female skeleton is less dense, smaller, and thinner than the male;{{cite book|last1=Patton |first1=Kevin T. |last2=Thibodeau |first2=Gary A. |title=Anthony's Textbook of Anatomy & Physiology - E-Book |date=2018 |publisher=Elsevier Health Sciences |isbn=9780323709309 |page=276 |url=https://books.google.com/books?id=_n1_DwAAQBAJ&pg=PA276}} its rib cage is more rounded and smaller, its lumbar curve greater, and a generally longer and smaller female waist results from the chest being more narrow at the base, and the pelvis generally not as high.

Studies show that men have a higher Bone Mineral Density(BMD) than women. It shows BMD values of approximately 3.88 g/cm² for men and 2.90 g/cm² for women, showing that male bones are 34% denser than female bones.{{Cite journal |last1=Langsetmo |first1=Lisa |last2=Leslie |first2=William D. |last3=Zhou |first3=Wei |last4=Goltzman |first4=David |last5=Kovacs |first5=Christopher S. |last6=Prior |first6=Jerilynn |last7=Josse |first7=Robert |last8=Olszynski |first8=Wojciech P. |last9=Davison |first9=K. Shawn |last10=Anastassiades |first10=Tassos |last11=Towheed |first11=Tanveer |last12=Hanley |first12=David A. |last13=Kaiser |first13=Stephanie |last14=Kreiger |first14=Nancy |last15=CaMOS Research Group |date=October 2010 |title=Using the same bone density reference database for men and women provides a simpler estimation of fracture risk |journal=Journal of Bone and Mineral Research |volume=25 |issue=10 |pages=2108–2114 |doi=10.1002/jbmr.112 |issn=1523-4681 |pmc=5101072 |pmid=20499356}}{{Cite journal |last1=Daly |first1=Robin M. |last2=Rosengren |first2=Bjorn E. |last3=Alwis |first3=Gayani |last4=Ahlborg |first4=Henrik G. |last5=Sernbo |first5=Ingemar |last6=Karlsson |first6=Magnus K. |date=2013-07-06 |title=Gender specific age-related changes in bone density, muscle strength and functional performance in the elderly: a-10 year prospective population-based study |journal=BMC Geriatrics |volume=13 |pages=71 |doi=10.1186/1471-2318-13-71 |doi-access=free |issn=1471-2318 |pmc=3716823 |pmid=23829776}} This makes females two times more likely to experience fractures in their lifetime compared to males, as well as a significantly higher risk of osteoporosis at old age.{{Cite journal |last1=Runolfsdottir |first1=Hrafnhildur L. |last2=Sigurdsson |first2=Gunnar |last3=Franzson |first3=Leifur |last4=Indridason |first4=Olafur S. |date=2015 |title=Gender comparison of factors associated with age-related differences in bone mineral density |url=https://pubmed.ncbi.nlm.nih.gov/26239743 |journal=Archives of Osteoporosis |volume=10 |pages=214 |doi=10.1007/s11657-015-0214-7 |issn=1862-3514 |pmid=26239743}}

The pelvis is, in general, different between the human female and male skeleton.{{cite book|last1=Iscan |first1=Mehmet Yasar |last2=Steyn |first2=Maryan |title=The Human Skeleton in Forensic Medicine: (3rd Ed.) |date=2013 |publisher=Charles C Thomas Publisher |isbn=9780398088798 |pages=146–147 |url=https://books.google.com/books?id=BhziCAAAQBAJ&pg=PA146}} Although variations exist and there may be a degree of overlap between typically male or female traits, the pelvis is the most dimorphic bone of the human skeleton and is therefore likely to be accurate when using it to ascertain a person's sex. It differs both in overall shape and structure. The female pelvis, which is adapted for gestation and childbirth, is less high, but proportionately wider and more circular than in the male; its sacrum—the triangular bone at the upper posterior of the pelvic cavity, serving as the base of the spine—is also wider. The female pelvis is tilted anteriorly, often resulting in the more sway-backed appearance.

In females, the acetabula, the concave surfaces to which the balls of the femurs attach via ligaments, are located farther apart,{{cite book|last=Amerman |first=Erin C. |title=Exploring Anatomy in the Laboratory, Second Edition |date=2021 |publisher=Morton Publishing Company |isbn=9781640431836 |page=163 |url=https://books.google.com/books?id=FoMTEAAAQBAJ&pg=PA163}}{{cite book|last=Delavier |first=Frédéric |title=Women's Strength Training Anatomy |date=2003 |publisher=Human Kinetics |isbn=9780736048132 |pages=44–45 |url=https://books.google.com/books?id=mKX9tAxwpG4C&pg=PA44}} which increases the distance between the most outer points of the femurs (their greater trochanters) and thus the width of the hips. Female femurs are therefore more generally angled (laterally, further away from vertical). This greater angle applies a larger portion of the gravitational or vertical load as valgus torque (rotational force against the knee). This, combined with the female's weaker tendons and ligaments and a narrower intercondylar notch, causes increased susceptibility to injury of the ACL in female athletes.{{cite book|last1=Magee |first1=David J. |last2=Zachazewski |first2=James E. |last3=Quillen |first3=William S. |last4=Manske |first4=Robert C. |title=Athletic and Sport Issues in Musculoskeletal Rehabilitation |date=2010 |publisher=Elsevier Health Sciences |isbn=9781437715729 |page=261 |url=https://books.google.com/books?id=3qF8q8VLWF8C&pg=PA261}}{{cite book|last1=Fernandez de las Penas |first1=Cesar |last2=Cleland |first2=Joshua |last3=Dommerholt |first3=Jan |title=Manual Therapy for Musculoskeletal Pain Syndromes: an evidence- and clinical-informed approach |date=2015 |publisher=Elsevier Health Sciences |isbn=9780702055775 |page=468 |url=https://books.google.com/books?id=J_wTDgAAQBAJ&pg=PA468}}

The pelvis of the human male is slightly narrower. One hypothesis is that this makes it more optimized for walking and that the wider female pelvis is an evolutionary compromise between efficient walking and the need for successful childbirth.{{cite book|last1=Thompson |first1=Tim |last2=Black |first2=Sue |title=Forensic Human Identification: An Introduction |date=2006 |publisher=CRC Press |isbn=9781420005714 |page=203 |url=https://books.google.com/books?id=IobMBQAAQBAJ&pg=PA203}} This is termed the obstetrical dilemma.{{cite book|last1=Geller |first1=Pamela L. |last2=Stockett |first2=Miranda K. |title=Feminist Anthropology: Past, Present, and Future |date=2007 |publisher=University of Pennsylvania Press |isbn=9780812220056 |pages=58–64 |url=https://books.google.com/books?id=SQVc_it2ohIC&pg=PA58}}{{cite journal|last1=Warrener |first1=Anna G. |last2=Lewton |first2=Kristi L. |last3=Pontzer |first3=Herman |last4=Lieberman |first4=Daniel E. |date=11 March 2015 |title=A Wider Pelvis Does Not Increase Locomotor Cost in Humans, with Implications for the Evolution of Childbirth |journal=PLOS ONE |volume=10 |issue=3 |pages=e0118903 |doi=10.1371/journal.pone.0118903 |pmc=4356512 |pmid=25760381 |bibcode=2015PLoSO..1018903W |doi-access=free}} Disagreement exists as to the strength of the hypothesis.

Males and females do not differ in their number of ribs; both normally have twelve pairs.{{cite book|last=Lawrence E. |first=Wineski |title=Snell's Clinical Anatomy Rehabilitation |date=2018 |publisher=Lippincott Williams & Wilkins |isbn=978-1975107024 |page=451 |url=https://books.google.com/books?id=tON1DwAAQBAJ&pg=PT451}}

The following further generalizations have been made regarding male-female skeletal differences:

• Males in general have denser, stronger bones, tendons, and ligaments.
• Female skulls and head bones differ in size and shape from the male skull, with the male mandible generally wider, larger, and squarer than the female.{{cite book|last=Burns |first=Karen Ramey |title=Forensic Anthropology Training Manual |date=2015 |publisher=Routledge |isbn=9781317348290 |page=198 |url=https://books.google.com/books?id=HDWDCgAAQBAJ&pg=PA198}} In addition, males generally have a more prominent brow, an orbital with rounded border, and more greatly projecting mastoid processes.
• Males have a more pronounced Adam's apple or thyroid cartilage and deeper voices due to larger vocal cords.{{cite book|last=Standring |first=Susan |title=Gray's Anatomy E-Book: The Anatomical Basis of Clinical Practice |date=2015 |publisher=Elsevier Health Sciences |isbn=9780702068515 |page=588 |url=https://books.google.com/books?id=b7FVCgAAQBAJ&pg=PA588}}
• Males have larger teeth than females and a greater proportion of the tooth in males is made up of dentine, whereas females have proportionately more enamel.{{cite book|last=Klales |first=Alexandra R. |title=Sex Estimation of the Human Skeleton: History, Methods, and Emerging Techniques |date=2020 |publisher=Academic Press |isbn=978-0128157688 |page=150 |url=https://books.google.com/books?id=FI_ODwAAQBAJ&pg=PA150}}

Pubertal changes in males lead to a ten times increase in testosterone. On average, adult males have 10-20 times more testosterone than adult females, with male testosterone levels ranging from 300 to 1,000 nanograms per deciliter (ng/dL), while adult females have testosterone levels between 15 and 70 ng/dL.{{Cite web |title=Testosterone: What It Is, Function & Levels |url=https://my.clevelandclinic.org/health/articles/24101-testosterone |archive-url=http://web.archive.org/web/20250405015804/https://my.clevelandclinic.org/health/articles/24101-testosterone |archive-date=2025-04-05 |access-date= |website=Cleveland Clinic |language=en}}{{Cite web |title=Content - Health Encyclopedia - University of Rochester Medical Center |url=https://www.urmc.rochester.edu/encyclopedia/content?contentid=testosterone_total&contenttypeid=167 |access-date= |website=www.urmc.rochester.edu}} It is because of the effects of testosterone that males tend to develop stronger muscles and denser bones.{{Cite web |date=2015-07-16 |title=Testosterone — What It Does And Doesn't Do |url=https://www.health.harvard.edu/staying-healthy/testosterone--what-it-does-and-doesnt-do? |access-date= |website=Harvard Health |language=en}} Also, males go through puberty for longer, thus females typically have lower total muscle mass than males, and also have lower muscle mass relative to total body mass. Males convert more of their caloric intake into muscle and expendable circulating energy reserves, while females tend to convert more into fat deposits.{{cite web |url=http://www.unm.edu/~lkravitz/Article%20folder/genderdifferences.html |title=Gender Differences in Fat Metabolism |publisher=The University of New Mexico |access-date=22 August 2014 |first1=Chantal |last1=Vella |first2=Len |last2=Kravitz}} As a consequence, males are generally physically stronger than females. Research suggests that, while males have greater total muscle areas than females, the number of muscle fibers in males and females are alike. Instead of muscle fiber composition as the main reason for male's greater absolute strength, the data indicates that it is total muscle area that is responsible for this difference.{{cite book|last=Legato |first=Marianne J. |title=Principles of Gender-Specific Medicine: Gender in the Genomic Era |date=2017 |publisher=Academic Press |isbn=978-0128035429 |pages=526, 528 |url=https://books.google.com/books?id=khATDgAAQBAJ&pg=PA526}} Males' individual muscle fibers are larger than women's, which results in their more muscular appearance. Their larger muscle fibers appear responsible for their more considerable absolute force production.

The sex difference in muscle mass still remains even after adjusting for body weight and height. Males are usually stronger than females when adjusting for differences in total body mass, due to the higher male muscle-mass to body-mass ratio.{{Cite journal |last1=Ben Mansour |first1=Ghassen |last2=Kacem |first2=Asma |last3=Ishak |first3=Mohamed |last4=Grélot |first4=Laurent |last5=Ftaiti |first5=Foued |date=2021-11-28 |title=The effect of body composition on strength and power in male and female students |journal=BMC Sports Science, Medicine and Rehabilitation |volume=13 |issue=1 |pages=150 |doi=10.1186/s13102-021-00376-z |doi-access=free |issn=2052-1847 |pmc=8628437 |pmid=34839825}} The greater muscle mass is reported to be due to a greater capacity for muscular hypertrophy as a result of higher levels of circulating testosterone in males.{{cite book |last1=Hoeger |first1=Wener W.K. |last2=Hoeger |first2=Sharon A. |title=Fitness and Wellness |date=2016 |publisher=Cengage Learning |isbn=978-1305887282 |page=250 |url=https://books.google.com/books?id=4XYcCgAAQBAJ&pg=PA250}}

The studies often show different results about the body strength difference between the both sexes. Two studies, conducted in the four European Union countries, involving 2,000 participants (1,000 men and 1 000 women) concluded that females are 74 - 92% as strong as males, as many women (211 of 1,000) are still physically stronger than average men.{{cite book |last1=Petrov |first1=Georgi |title=The Human nature and The Society |page=55 |quote=One of the most controversial topics is the difference in physical strength and weather it exist. In 2008 two independent studies, made from 6 universities in Netherlands, Sweden, France and Denmark, involving 2,000 participants, of which 1,000 men and 1,000 women proves that adult female participants are 74 - 92 % as strong as males on average. But many women still physically stronger than average men, after 211 of females performed better than average level of males at the physical test. |date=2012 |publisher=Bulgarressurs |isbn=9789548885119}}{{cite book |last1=Yankov|first1=Yanko|title=How our brain evolved to become human |page=187 |quote=Cultural factors also have a large influence. Although it is widely considered that males still outperform females on average, many women are much stronger than the average man. Studies by Western European scientists of 1,000 men and 1,000 women showed that 211 of the women performed better than the men's average, proving that the evolution of physical strength in humans is still uncharted territory.|date=2023|publisher=Fakel|isbn=9789544113278}} The differences is smaller in lower body strength and higher in upper body strength.

Some researches shows gross measures of body strength suggest that females are approximately 50-60% as strong as males in the upper body, and 60-70% as strong in the lower body.{{cite journal |last1=Miller |first1=A.E. |last2=MacDougall |first2=J.D. |last3=Tarnopolsky |first3=M.A. |last4=Sale |first4=D.G. |title=Gender differences in strength and muscle fiber characteristics |journal=European Journal of Applied Physiology and Occupational Physiology |volume=66 |issue=3 |pages=254–62 |year=1993 |pmid=8477683 |doi=10.1007/BF00235103 |hdl=11375/22586 |s2cid=206772211 |hdl-access=free}} One study of muscle strength in the elbows and knees—in 45 and older males and females—found the strength of females to range from 42 to 63% of male strength.{{cite journal |last1=Frontera |first1=W.R. |last2=Hughes |first2=V.A. |last3=Lutz |first3=K.J. |last4=Evans |first4=W.J. |title=A cross-sectional study of muscle strength and mass in 45- to 78-yr-old men and women |journal=Journal of Applied Physiology |volume=71 |issue=2 |pages=644–50 |date=August 1991 |pmid=1938738 |doi=10.1152/jappl.1991.71.2.644}} Males have greater hand grip strength than females.{{cite book|last=Holtz |first=Jan Leslie |title=Applied Clinical Neuropsychology: An Introduction |date=2010 |publisher=Springer Publishing Company |isbn=978-0826104748 |page=224 |url=https://books.google.com/books?id=Wgo_Cq277JQC&pg=PA224}}{{cite book|title=World Report on Ageing and Health |date=2015 |publisher=World Health Organization |isbn=978-9241565042 |page=53 |url=https://books.google.com/books?id=n180DgAAQBAJ&pg=PA53}} Differences in width of arm, thighs and calves appear during puberty.

Males typically have larger lungs than females.{{cite book |doi=10.1007/978-3-030-63549-7_2 |chapter=Sex Differences in the Anatomy of the Airways and the Lungs: Impact on Dysanapsis across the Lifespan |title=Sex-Based Differences in Lung Physiology |series=Physiology in Health and Disease |year=2021 |last1=Lomauro |first1=Antonella |last2=Aliboni |first2=Lorenzo |last3=Aliverti |first3=Andrea |publisher=Springer Science+Business Media |pages=13–38 |isbn=978-3-030-63548-0 |s2cid=234284090 |chapter-url=https://books.google.com/books?id=rcIkEAAAQBAJ&pg=PA22}} On average, males have a total lung capacity (TLC) of 6 litres, while females have a total lung capacity of 4.2 litres.{{Cite journal |last1=Ekström |first1=Magnus |last2=Sundh |first2=Josefin |last3=Schiöler |first3=Linus |last4=Lindberg |first4=Eva |last5=Rosengren |first5=Annika |last6=Bergström |first6=Göran |last7=Angerås |first7=Oskar |last8=Hedner |first8=Jan |last9=Brandberg |first9=John |last10=Bake |first10=Björn |last11=Torén |first11=Kjell |date=2018-01-05 |title=Absolute lung size and the sex difference in breathlessness in the general population |journal=PLOS ONE |language=en |volume=13 |issue=1 |pages=e0190876 |doi=10.1371/journal.pone.0190876 |doi-access=free |pmid=29304074 |pmc=5755925 |bibcode=2018PLoSO..1390876E |issn=1932-6203}} Even when males and females are matched for height and body size in a controlled comparison, males still tend to have 12% greater lung volume relative to body mass.{{Citation |last1=Sathish |first1=Venkatachalem |title=Chapter 6 - Sex Differences in Pulmonary Anatomy and Physiology: Implications for Health and Disease |date=2016-01-01 |work=Sex Differences in Physiology |pages=89–103 |editor-last=Neigh |editor-first=Gretchen N. |url=https://www.sciencedirect.com/science/article/abs/pii/B9780128023884000069 |access-date=2025-04-18 |place=Boston |publisher=Academic Press |isbn=978-0-12-802388-4 |last2=Prakash |first2=Y. S. |editor2-last=Mitzelfelt |editor2-first=Megan M.}} On average, males have larger airways, with the trachea and bronchi being approximately 35% larger in males than in females.{{Cite book |last1=Silveyra |first1=Patricia |url=https://books.google.com/books?id=rcIkEAAAQBAJ&pg=PA22 |title=Sex-Based Differences in Lung Physiology |last2=Tigno |first2=Xenia T. |date=2021-03-18 |publisher=Springer Nature |isbn=978-3-030-63549-7 |pages=13–18 |language=en}}

On average, male hearts are approximately 31% larger than female hearts in absolute terms (i.e., without adjusting for body size).{{Cite journal |last1=Martin |first1=Thomas G. |last2=Leinwand |first2=Leslie A. |date=2024-07-01 |title=Hearts apart: sex differences in cardiac remodeling in health and disease |journal=The Journal of Clinical Investigation |language=en |volume=134 |issue=13 |pages=e180074 |doi=10.1172/JCI180074 |pmid=38949027 |issn=0021-9738|pmc=11213513 }}{{cite book|last1=Cotes |first1=John E. |last2=Maynard |first2=Robert L. |last3=Pearce |first3=Sarah J. |last4=Nemery |first4=Benoit B. |last5=Wagner |first5=Peter D. |last6=Cooper |first6=Brendan G. |title=Lung Function |date=2020 |publisher=John Wiley & Sons |isbn=978-1-11-859735-4 |page=450 |url=https://books.google.com/books?id=5n_PDwAAQBAJ&pg=PA450}} In controlled comparisons—where height and body size are matched—male hearts are still, on average 25% larger than female hearts, particularly due to greater left ventricular (LV) mass, larger atrial and ventricular cavities, and thicker ventricular walls and chambers in males.{{Cite journal |last1=Rønningen |first1=Peter Selmer |last2=Berge |first2=Trygve |last3=Solberg |first3=Magnar Gangås |last4=Enger |first4=Steve |last5=Nygård |first5=Ståle |last6=Pervez |first6=Mohammad Osman |last7=Orstad |first7=Eivind Bjørkan |last8=Kvisvik |first8=Brede |last9=Aagaard |first9=Erika Nerdrum |last10=Røsjø |first10=Helge |last11=Tveit |first11=Arnljot |last12=Steine |first12=Kjetil |date=2020-05-01 |title=Sex differences and higher upper normal limits for left atrial end-systolic volume in individuals in their mid-60s: data from the ACE 1950 Study |url=https://academic.oup.com/ehjcimaging/article-abstract/21/5/501/5730218 |journal=European Heart Journal - Cardiovascular Imaging |volume=21 |issue=5 |pages=501–507 |doi=10.1093/ehjci/jeaa004 |pmid=32031593 |issn=2047-2404|hdl=10852/102297 |hdl-access=free }}{{Cite journal |last1=Westaby |first1=Joseph David |last2=Zullo |first2=Emelia |last3=Bicalho |first3=Luciana Morais |last4=Anderson |first4=Robert Henry |last5=Sheppard |first5=Mary Noelle |date=2023 |title=Effect of sex, age and body measurements on heart weight, atrial, ventricular, valvular and sub-epicardial fat measurements of the normal heart |url=https://pubmed.ncbi.nlm.nih.gov/36442703 |journal=Cardiovascular Pathology |volume=63 |pages=107508 |doi=10.1016/j.carpath.2022.107508 |issn=1879-1336 |pmid=36442703|doi-access=free }} For example, one study reported a mean heart mass of 374 ± 64 grams in males and 285 ± 55 grams in females.{{Cite journal |last1=St. Pierre |first1=Sarah R. |last2=Peirlinck |first2=Mathias |last3=Kuhl |first3=Ellen |date=2022-03-22 |title=Sex Matters: A Comprehensive Comparison of Female and Male Hearts |journal=Frontiers in Physiology |language=English |volume=13 |doi=10.3389/fphys.2022.831179 |doi-access=free |pmid=35392369 |pmc=8980481 |issn=1664-042X}} Males also have, on average 10% higher red blood cell count, and higher haemoglobin hence greater oxygen-carrying capacity.{{cite book|last=Heuer |first=Albert J. |title=Wilkins' Clinical Assessment in Respiratory Care |date=2017 |publisher=Elsevier Health Sciences |isbn=978-0-32-351166-7 |page=126 |url=https://books.google.com/books?id=yt3WDwAAQBAJ&pg=PA126}}{{cite book|last1=Dunford |first1=Marie |last2=Doyle |first2=Andrew |title=Nutrition for Sport and Exercise |date=2021 |publisher=Cengage Learning |isbn=978-0-35-744827-4 |page=98 |url=https://books.google.com/books?id=alUzEAAAQBAJ&pg=PA98}} They have higher circulating clotting factors (vitamin K, prothrombin and platelets). These differences lead to faster clotting of blood and higher peripheral pain tolerance.{{cite book|title=Sexual Dimorphism in Human and Mammalian Biology and Pathology |last=Glucksman |first=A. |publisher=Academic Press |year=1981 |pages=66–75}}

Sex differences in the trachea and main bronchi are not apparent until at least age 14. On average, females have smaller lungs than males at birth.

{{See also|Androgenic hair|Human skin}}

File:Woman showing fullness of cheeks.jpg

Males' skin is thicker and oilier than females' skin.{{Cite book|last1=Nait-Ali|first1=Amine|title=Biometrics under Biomedical Considerations |date=2018|publisher=Springer|isbn=978-9-81-131144-4|page=121|url=https://books.google.com/books?id=J3B_DwAAQBAJ&pg=PA121}} Females have more subcutaneous fat than males. This helps keep them warmer and enables them to survive lower temperatures than males during the cold.{{Cite book|last1=Vij|first1=Krishan|title=Textbook of Forensic Medicine & Toxicology: Principles & Practice - e-book|date=2013|publisher=Elsevier Health Sciences|isbn=978-8-13-123623-9|page=171|url=https://books.google.com/books?id=Ip1rAwAAQBAJ&pg=PA171}} As a result of greater vasoconstriction, while the surface of female skin is colder than male skin, the deep-skin temperature in females is higher than in males.{{cite journal |last1=Malkinson |first1=T.J. |last2=Martin |first2=S. |last3=Simper |first3=P. |last4=Cooper |first4=K.E. |title=Expired air volumes of males and females during cold water immersion |journal=Canadian Journal of Physiology and Pharmacology |volume=59 |issue=8 |pages=843–6 |date=August 1981 |pmid=7296382 |doi=10.1139/y81-125}} Males have less subcutaneous fat in their faces due to the effects of testosterone.{{Cite web |last=Admin |date=2019-07-30 |title=Jawlines: Understanding Gender Differences, Facial Ageing and Defining |url=https://www.ifaas.co/single-post/jawlines-understanding-gender-differences-facial-ageing-and-defining-using-super-embossed-threads-an |access-date=2024-11-24 |website=ifaas |language=en}}{{bsn|date=November 2024}}

Males generally have darker skin than females.{{cite journal |last1=Firooz |first1=Alireza |last2=Sadr |first2=Bardia |last3=Babakoohi |first3=Shahab |last4=Sarraf-Yazdy |first4=Maryam |last5=Fanian |first5=Ferial |last6=Kazerouni-Timsar |first6=Ali |last7=Nassiri-Kashani |first7=Mansour |last8=Naghizadeh |first8= Mohammad Mehdi |last9=Dowlati |first9=Yahya |title=Variation of Biophysical Parameters of the Skin with Age, Gender, and Body Region |journal=The Scientific World Journal |date=2012 |doi=10.1100/2012/386936 |volume=2012 |pages=386936 |pmid=22536139 |pmc=3317612 |doi-access=free }} The lighter skin in females helps their bodies synthesize more Vitamin D from sunlight and absorb more calcium, which is needed during pregnancy and lactation.{{cite journal |last1=Jablonski |first1=N.G. |last2=Chaplin |first2=G. |title=The evolution of human skin coloration |journal=Journal of Human Evolution |volume=39 |issue=1 |pages=57–106 |date=July 2000 |pmid=10896812 |doi=10.1006/jhev.2000.0403 |bibcode=2000JHumE..39...57J |s2cid=38445385 }}

On average, males have more body hair than females. Males have relatively more of a type of hair called terminal hair, especially on the face, chest, abdomen and back. Females have more vellus hair, which is thinner, shorter, and lighter, and therefore less visible.{{cite journal|last1=Giacomoni |first1=P.U. |last2=Mammone |first2=T. |last3=Teri |first3=M. |title=Gender-linked differences in human skin. |journal=Journal of Dermatological Science |date=September 2009 |volume=55 |issue=3 |pages=144–9 |pmid=19574028 |doi=10.1016/j.jdermsci.2009.06.001}}

Although males grow hair faster than females, baldness is more prevalent in males than in females. The main cause for this is male pattern baldness. Male pattern baldness is a condition where hair loss occurs in a typical pattern of a receding hairline and hair thinning on the crown. It is caused by hormones and genetic predisposition.{{cite web|title=Male pattern baldness |url=https://www.nlm.nih.gov/medlineplus/ency/article/001177.htm |website=MedlinePlus |publisher=United States National Library of Medicine |access-date=25 August 2015}}

File:Woman redhead natural portrait.jpg and blond hair are more common in females than in males (red more so than blond).]]

In lighter-complected humans, male skin is visibly redder; this is due to greater blood volume rather than melanin.{{cite journal |last1=Wennesland |first1=R. |last2=Brown |first2=E. |last3=Hopper |first3=J |others=etal |title=Red cell, plasma and blood volume in healthy men measured by radiochromium (Cr51) cell tagging and hematocrit: influence of age, somatotype and habits of physical activity on the variance after regression of volumes to height and weight combined |journal=Journal of Clinical Investigation |volume=38 |issue=7 |pages=1065–77 |date=July 1959 |pmid=13664782 |pmc=293254 |doi=10.1172/JCI103883}}{{cite journal |last1=Fortney |first1=S.M. |last2=Nadel |first2=E.R. |last3=Wenger |first3=C.B. |last4=Bove |first4=J.R. |title=Effect of blood volume on sweating rate and body fluids in exercising humans |journal=Journal of Applied Physiology: Respiratory, Environmental and Exercise Physiology |volume=51 |issue=6 |pages=1594–600 |date=December 1981 |pmid=7319888 |doi=10.1152/jappl.1981.51.6.1594}} Conversely, females are lighter-skinned than males in some studied human populations.{{cite book|last=Jablonski |first=Nina |title=Living Color |year=2012 |publisher=University of California Press |location=Berkeley, Los Angeles, London |isbn=978-0-520-25153-3}}{{page needed|date=August 2014}}{{cite journal |url=http://courses.washington.edu/bioa101/articles/article33.pdf |title=Skin Deep |publisher=University of Washington |access-date=22 August 2014 |first1=Nina G. |last1=Jablonski |first2=George |last2=Chaplin |journal=Scientific American |year=2002 |volume=287 |issue=4 |pages=74–81 |doi=10.1038/scientificamerican1002-74 |pmid=12271527 |bibcode=2002SciAm.287d..74J |name-list-style=amp |archive-url=https://web.archive.org/web/20131024111128/http://courses.washington.edu/bioa101/articles/article33.pdf |archive-date=24 October 2013 |url-status=dead |df=dmy-all}} The differences in color are mainly caused by higher levels of melanin in the skin, hair and eyes in males.{{cite journal |author=Frost P |title=Human skin color: a possible relationship between its sexual dimorphism and its social perception |journal=Perspectives in Biology and Medicine |volume=32 |issue=1 |pages=38–58 |year=1988 |pmid=3059317 |doi=10.1353/pbm.1988.0010 |s2cid=36144428}}{{cite journal |doi=10.1016/j.evolhumbehav.2005.07.002 |last1=Frost |first1=P. |year=2006 |title=European hair and eye color - A case of frequency-dependent sexual selection? |url=https://zenodo.org/record/889906 |journal=Evolution and Human Behavior |volume=27 |issue=2 |pages=85–103|bibcode=2006EHumB..27...85F }}

In one study, almost twice as many females as males had red or auburn hair. A higher proportion of females were also found to have blond hair, whereas males were more likely to have black or dark brown hair.{{cite journal |vauthors=Duffy DL, Montgomery GW, Chen W, etal |title=A Three–Single-Nucleotide Polymorphism Haplotype in Intron 1 of OCA2 Explains Most Human Eye-Color Variation |journal=American Journal of Human Genetics |volume=80 |issue=2 |pages=241–52 |date=February 2007 |pmid=17236130 |pmc=1785344 |doi=10.1086/510885}} Another study found green eyes, which are a result of lower melanin levels, to be much more common in females than in males, at least by a factor of two.{{cite web|last=Frost |first=P. |date=2007 |url=http://evoandproud.blogspot.com/2007/11/sex-linkage-of-human-skin-hair-and-eye.html |title=Sex linkage of human skin, hair, and eye color}}{{cite journal |last1=Sulem |first1=Patrick |last2=Gudbjartsson |first2=Daniel F. |last3=Stacey |first3=Simon N. |last4=Helgason |first4=Agnar |last5=Rafnar |first5=Thorunn |last6=Magnusson |first6=Kristinn P. |last7=Manolescu |first7=Andrei |last8=Karason |first8=Ari |last9=Palsson |first9=Arnar |last10=Thorleifsson |first10=Gudmar |last11=Jakobsdottir |first11=Margret |last12=Steinberg |first12=Stacy |last13=Pálsson |first13=Snæbjörn |last14=Jonasson |first14=Fridbert |last15=Sigurgeirsson |first15=Bardur |last16=Thorisdottir |first16=Kristin |last17=Ragnarsson |first17=Rafn |last18=Benediktsdottir |first18=Kristrun R. |last19=Aben |first19=Katja K. |last20=Kiemeney |first20=Lambertus A. |last21=Olafsson |first21=Jon H. |last22=Gulcher |first22=Jeffrey |last23=Kong |first23=Augie |last24=Thorsteinsdottir |first24=Unnur |last25=Stefansson |first25=Kari |title=Genetic determinants of hair, eye and skin pigmentation in Europeans |journal=Nature Genetics |volume=39 |issue=12 |pages=1443–52 |year=2007 |pmid=17952075 |doi=10.1038/ng.2007.13 |s2cid=19313549 |display-authors=8}}

A different study found that while females tend to have a lower frequency of black hair, males have a higher frequency of platinum blond hair, blue eyes and lighter skin. According to this one theory the cause for this is a higher frequency of genetic recombination in females than in males, possibly due to sex-linked genes, and as a result females tend to show less phenotypical variation in any given population.{{cite journal |last1=Branicki |first1=Wojciech |last2=Brudnik |first2=Urszula |last3=Wojas-Pelc |first3=Anna |title=Interactions Between HERC2, OCA2 and MC1R May Influence Human Pigmentation Phenotype |journal=Annals of Human Genetics |volume=73 |issue=2 |pages=160–170 |year=2009 |pmid=19208107 |doi=10.1111/j.1469-1809.2009.00504.x |s2cid=5233533}}[http://dienekes.blogspot.com/2009/02/interaction-between-loci-affecting.html Interaction between loci affecting human pigmentation in Poland]{{cite journal|last1=Aoki |first1=K. |title=Sexual selection as a cause of human skin colour variation: Darwin's hypothesis revisited. |journal=Annals of Human Biology |date=2002 |volume=29 |issue=6 |pages=589–608 |pmid=12573076 |doi=10.1080/0301446021000019144 |s2cid=22703861}}

The human sexual dimorphism in color seems to be greater in populations that are medium in skin color than in very light or very dark-colored populations.

{{See also|Human male reproductive system|Human female reproductive system}}

File:Male anatomy 1.png.]] File:Scheme female reproductive system-en.svg.]]

File:1116_Muscle_of_the_Perineum.jpg]]

Males and females have different sex organs. Females have two ovaries that store the eggs, and a uterus which is connected to a vagina. The external genitals are called the vulva. Males have testicles that produce sperm. The testicles are placed in the scrotum behind the penis, which are external extremities.{{Cite web |title=The Reproductive System {{!}} Loma Linda University Fertility |url=https://lomalindafertility.com/pregnancy/reproductive-system/ |access-date=2024-01-20 |website=Loma Linda University Center for Fertility & IVF |language=en-US}}

Male orgasm (and the corresponding release of ejaculate containing sperm from the testes) is essential for reproduction, whereas female orgasm is not. The female orgasm was originally believed to have no function other than pleasure. Later evidence suggests that it evolved as a discriminatory advantage in regards to mate selection.{{cite web|url=https://www.psychologytoday.com/articles/199601/the-orgasm-wars |website=Psychology Today |title=The Orgasm Wars}}

Female ejaculation has been observed for 2,000 years. It refers to the release of fluid experienced by some females during orgasm. The components of the ejaculate are comparable to that of the male ejaculate. The release of this fluid is a product of the Skene's gland (female prostate), located within the walls of the urethra. The female prostate is much smaller than the male prostate but seems to behave in a similar fashion. Female ejaculate, though, does not contain sperm.{{cite journal |author1=Korda JB |author2=Goldstein SW |author3=Sommer F |title=The history of female ejaculation |journal=The Journal of Sexual Medicine |volume=7 |issue=5 |pages=1965–75 |date=May 2010 |pmid=20233286 |doi=10.1111/j.1743-6109.2010.01720.x}} The female prostate is visible through MRI and ultrasound.

Males typically produce billions of sperm each month,{{MedlinePlusEncyclopedia|003627|Semen analysis}} many of which are capable of fertilization. Females typically produce one ovum a month that can be fertilized into an embryo. Thus during a lifetime males are able to father a significantly greater number of children than females can give birth to. The most fertile female, according to the Guinness Book of World Records, was Valentina Vassilyev of Russia (1707–1782) who had 69 surviving children. The most prolific father of all time is believed to be the last Sharifian Emperor of Morocco, Mulai Ismail (1646–1727) who reportedly fathered more than 800 children from a harem of 500 women.

Males undergo a greater number of germline cell divisions than females, and as a consequence the male germline accumulates more DNA replication errors that result in a higher mutation rate in males than in females.{{cite journal | doi=10.1007/s00239-005-0308-8 | title=Mammalian Male Mutation Bias: Impacts of Generation Time and Regional Variation in Substitution Rates | date=2006 | last1=Goetting-Minesky | first1=M. Paula | last2=Makova | first2=Kateryna D. | journal=Journal of Molecular Evolution | volume=63 | issue=4 | pages=537–544 | pmid=16955237 | bibcode=2006JMolE..63..537G }}

Female fertility declines after age 30 and ends with the menopause.[http://www.fertilitylifelines.com/fertilityhealth/age.jsp Graph] {{webarchive|url=https://web.archive.org/web/20071027074628/http://www.fertilitylifelines.com/fertilityhealth/age.jsp |date=2007-10-27}} @ FertilityLifelines.[http://www.epigee.org/health/infertility.html Graph] @ Epigee.org. Female physical experiences vary depending on external forces such as diet, marriage patterns, culture, and other aspects. In Western nations menstruation begins to affect females at 13 and menopause starts around 51. In non-industrialized countries, on the other hand, most females begin menstruation at a later age.{{cite journal|last1=Karapanou |first1=O. |last2=Papadimitriou |first2=A. |title=Determinants of menarche. |journal=Reproductive Biology and Endocrinology |date=30 September 2010 |volume=8 |pages=115 |pmid=20920296 |doi=10.1186/1477-7827-8-115 |pmc=2958977 |doi-access=free }} More lactation in the lifetime of non-western females inhibits ovulation and extends the number of fertile years.{{cite book|title=Has feminism changed science? |first=Londa |last=Schiebinger |location=Cambridge, Massachusetts |publisher=Harvard University Press |date=1999 |pages=120–121}} Pregnancy in the 40s or later has been correlated with increased risk of Down syndrome in children.{{cite web|url=http://www.asrm.org/Patients/patientbooklets/agefertility.pdf |title=Age and Fertility: A Guide for Patients |website=American Society for Reproductive Medicine |date=2003}} Males are capable of fathering children into old age. Paternal age effects in children include multiple sclerosis,{{cite journal |last1=Montgomery |first1=S.M. |last2=Lambe |first2=M. |last3=Olsson |first3=T. |last4=Ekbom |first4=A. |title=Parental age, family size, and risk of multiple sclerosis |journal=Epidemiology |volume=15 |issue=6 |pages=717–23 |date=November 2004 |pmid=15475721 |doi=10.1097/01.ede.0000142138.46167.69|s2cid=14813112 |doi-access=free }} autism,{{cite journal |vauthors=Reichenberg A, Gross R, Weiser M, etal |title=Advancing paternal age and autism |journal=Archives of General Psychiatry |volume=63 |issue=9 |pages=1026–32 |date=September 2006 |pmid=16953005 |doi=10.1001/archpsyc.63.9.1026 |doi-access=}} breast cancer{{cite journal |vauthors=Choi JY, Lee KM, Park SK, etal |title=Association of paternal age at birth and the risk of breast cancer in offspring: a case control study |journal=BMC Cancer |volume=5|pages=143 |year=2005 |pmid=16259637 |pmc=1291359 |doi=10.1186/1471-2407-5-143 |doi-access=free }} and schizophrenia,{{cite journal |vauthors=Sipos A, Rasmussen F, Harrison G, etal |title=Paternal age and schizophrenia: a population based cohort study |journal=British Medical Journal |volume=329 |issue=7474 |pages=1070 |date=November 2004 |pmid=15501901 |pmc=526116 |doi=10.1136/bmj.38243.672396.55}} as well as reduced intelligence.{{cite journal |vauthors=Saha S, Barnett AG, Foldi C, etal |editor1-last=Brayne |editor1-first=Carol |title=Advanced Paternal Age Is Associated with Impaired Neurocognitive Outcomes during Infancy and Childhood |journal=PLOS Medicine |volume=6 |issue=3 |pages=e40 |date=March 2009 |pmid=19278291 |pmc=2653549 |doi=10.1371/journal.pmed.1000040 |doi-access=free }}

Adriana Iliescu was reported as the world's oldest woman to give birth, at age 66. Her record stood until Maria del Carmen Bousada de Lara gave birth to twin sons at Sant Pau Hospital in Barcelona, Spain on December 29, 2006, at the age of 67. In both cases IVF was used. The oldest known father was former Australian miner Les Colley, who fathered a child at age 93.[https://archive.today/20120717033026/http://health.dailynewscentral.com/content/view/310/63 oldest birth parents]

{{Main|Neuroscience of sex differences}}

The brains of humans were long believed to be different for males and females.{{cite book |first1=Robert W. |last1=Goy |first2=Bruce S. |last2=McEwen |title=Sexual Differentiation of the Brain: Based on a Work Session of the Neurosciences Research Program |publisher=MIT Press Classics |location=Boston |date=1980 |url=https://mitpress.mit.edu/catalog/item/default.asp?ttype=2&tid=10042&mode=toc |archive-url=https://web.archive.org/web/20110604094727/https://mitpress.mit.edu/catalog/item/default.asp?ttype=2&tid=10042&mode=toc |archive-date=4 June 2011}} However, this has been called into question by recent developments in neuroscience. For example, studies published in 2018,{{Cite journal |last1=Joel |first1=Daphna |last2=Persico |first2=Ariel |last3=Salhov |first3=Moshe |last4=Berman |first4=Zohar |last5=Oligschläger |first5=Sabine |last6=Meilijson |first6=Isaac |last7=Averbuch |first7=Amir |date=2018 |title=Analysis of Human Brain Structure Reveals that the Brain "Types" Typical of Males Are Also Typical of Females, and Vice Versa |journal=Frontiers in Human Neuroscience |volume=12 |page=399 |doi=10.3389/fnhum.2018.00399 |doi-access=free |pmid=30405373 |pmc=6204758 |issn=1662-5161}} 2019,{{Cite journal |title=APA PsycNet |journal=American Psychologist |date=February 2019 |volume=74 |issue=2 |pages=171–193 |doi=10.1037/amp0000307 |language=en |last1=Hyde |first1=Janet Shibley |last2=Bigler |first2=Rebecca S. |last3=Joel |first3=Daphna |last4=Tate |first4=Charlotte Chucky |last5=Van Anders |first5=Sari M. |pmid=30024214 |doi-access=free }} and 2021,{{Cite journal |last1=Eliot |first1=Lise |last2=Ahmed |first2=Adnan |last3=Khan |first3=Hiba |last4=Patel |first4=Julie |date=2021-06-01 |title=Dump the "dimorphism": Comprehensive synthesis of human brain studies reveals few male-female differences beyond size |journal=Neuroscience & Biobehavioral Reviews |volume=125 |pages=667–697 |doi=10.1016/j.neubiorev.2021.02.026 |pmid=33621637 |issn=0149-7634|doi-access=free }} among others, have challenged the idea of sexual dimorphism regarding the brain, with one study concluding firmly that "brains are not meaningfully aligned along a male-female continuum."{{Cite journal |last=Joel |first=Daphna |date=2021-03-01 |title=Beyond the binary: Rethinking sex and the brain |journal=Neuroscience & Biobehavioral Reviews |volume=122 |pages=165–175 |doi=10.1016/j.neubiorev.2020.11.018 |pmid=33440198 |issn=0149-7634|doi-access=free }} When the size of one's head is accounted for, brain differences between sexes are no longer clear, and they are not generalizable across geographic regions (i.e., what is considered a brain sex distinction in Europeans may not correlate to sex distinctions between Asian populations).{{Cite web |last=Eliot |first=Lise |date=2021-04-22 |title=You don't have a male or female brain – the more brains scientists study, the weaker the evidence for sex differences |url=http://theconversation.com/you-dont-have-a-male-or-female-brain-the-more-brains-scientists-study-the-weaker-the-evidence-for-sex-differences-158005 |access-date=2024-01-20 |website=The Conversation |language=en-US}}

File:Lobes of the brain NL.svg

Early research into the differences between male and female brains showed that male brains are, on average, larger than female brains. This research was frequently cited to support the assertion that women are less intelligent than men.{{cite book|last=Gould |first=Stephen Jay |author-link=Stephen Jay Gould |title=The Panda's Thumb |url=https://archive.org/details/pandasthumbmorer00goul |url-access=registration |year=1980 |publisher=Norton |location=New York |isbn=978-0393308198 |pages=[https://archive.org/details/pandasthumbmorer00goul/page/152 152–159]}} One of the most influential early researchers on this topic was Paul Broca. In 1861, he examined 432 human brains from cadavers and found that the brains of males had an average weight of 1325 grams, while the brains of females had an average weight of 1144 grams. This study, however, did not control for differences in body size or age.{{cite journal |last1=Fee |first1=Elizabeth |year=1979 |title=Nineteenth-Century Craniology: The Study of the Female Skull |journal=Bulletin of the History of Medicine |volume=53 |issue=3 |pages=415–53 |pmid=394780}} Later studies have shown that while male's brains are an average of 10-15% larger and heavier than female's brains, there is relatively no difference when controlling for body weight. This means the brain-to-body mass ratio is, on average, approximately the same for both sexes. Comparing a male and a female of the same body size, an average difference of 100 grams in brain-mass is present, the male having the bigger and heavier brain. This difference of 100 grams applies over the whole range of human sizes.{{cite book |author-link=Doreen Kimura |last=Kimura |first=Doreen |year=1999 |title=Sex and Cognition |publisher=MIT Press |pages=127–8 |isbn=978-0-262-11236-9}}{{cite journal |doi=10.1016/0191-8869(93)90031-W |url=https://www.researchgate.net/publication/222481902 |title=Corrections to a paper on race and sex differences in brain size and intelligence |year=1993 |last1=Rushton |first1=J. Philippe |journal=Personality and Individual Differences |volume=15 |issue=2 |pages=229–231}}

File:Human brain right dissected lateral view description.JPG relative to grey matter.]]

Structural brain differences usually correspond to sexually dimorphic attributes that bring about functional brain differences.

On average, female brains have a larger ratio of grey matter to the white matter than males (particularly in the dorsolateral prefrontal cortex and superior temporal gyrus), even when sex-differences in the total intracranial volume are taken into consideration. Most notably, males have a larger amount of white matter in the frontal and temporal perisylvian region, and in the temporal stem and optic radiation, of the left hemisphere, whereas females have a larger amount of gray matter in the superior temporal gyrus, planum temporale, Heschl gyrus, cingulate gyrus, inferior frontal, and central sulci margins, of the left hemisphere.

The degree of hemispheric asymmetry in males corresponds to the relative size of corpus callosum; however, this is not true in females. An increase in hemispheric asymmetry in male brains causes a male sex-dependent decrease in inter-hemispheric connectivity. Many studies suggest that, on average, female brains have more commissural tracts involved in inter-hemispheric connectivity than males. Specifically, studies suggests that:

• The anterior commissure is larger in females than males.
• The massa intermedia is more abundant in females than males.
• Females have a larger ratio of the cross-sectional area of the corpus callosum to cerebral volume and to forebrain size than males.

Several studies have reached contrary conclusions.

There are also differences in the structure of specific areas of the brain. On average, the SDN has been repeatedly found to be considerably larger in males than in females. The volume of the SDN was 2.2 times as large in males as in females. On average, the BSTc is twice as large in males as in females. On average, the INAH-3 is significantly larger in males than in females regardless of age. Two studies found that men have larger parietal lobes, an area responsible for sensory input including spatial sense and navigation; though, another study failed to find any statistically significant difference.{{cite journal |last1=Frederikse |first1=M.E. |last2=Lu |first2=A. |last3=Aylward |first3=E. |last4=Barta |first4=P. |last5=Pearlson |first5=G. |title=Sex differences in the inferior parietal lobule |journal=Cerebral Cortex |volume=9 |issue=8 |pages=896–901 |date=December 1999 |pmid=10601007 |doi=10.1093/cercor/9.8.896 |doi-access=free}}{{cite book|last=Ellis |first=Lee |title=Sex differences: summarizing more than a century of scientific research |publisher=CRC Press |date=2008}} At the same time, females have larger Wernicke's and Broca's areas, areas responsible for language processing.{{cite journal |last1=Harasty |first1=J. |last2=Double |first2=K.L. |last3=Halliday |first3=G.M. |last4=Kril |first4=J.J. |last5=McRitchie |first5=D.A. |title=Language-associated cortical regions are proportionally larger in the female brain |journal=Archives of Neurology |volume=54 |issue=2 |pages=171–6 |date=February 1997 |pmid=9041858 |doi=10.1001/archneur.1997.00550140045011}} Studies using MRI scanning have shown that the auditory and language-related regions in the left hemisphere are proportionally expanded in females versus in males. Conversely, the primary visual, and visuo-spatial association areas of the parietal lobes are proportionally larger in males.{{cite journal|doi=10.1097/WNR.0b013e32832c5e65 |last1=Brun |first1=C.C. |last2=Leporé |first2=N. |last3=Luders |first3=E. |last4=Chou |first4=Y.Y. |last5=Madsen |first5=S.K. |last6=Toga |first6=A.W. |last7=Thompson |first7=P.M. |title=Sex differences in brain structure in auditory and cingulate regions |journal=NeuroReport |volume=20 |issue=10 |pages=930–935 |year=2009 |pmid=19562831 |pmc=2773139 |display-authors=etal}} The corpus callous is located at the sagittal divide and is the primary commissure in the human brain. It connects the left and right hemispheres of the cerebral cortex, which allows them to communicate with each other. With respect to language, males predominantly use their left hemisphere but females use both their right and left hemispheres. The right hemisphere controls emotion, so using the right hemisphere adds more prosody to speech.{{cite book|last=Carlson |first=Neil R. |title=Physiology of Behavior |year=2007 |publisher=Pearson Allyn & Bacon |location=Boston |isbn=978-0205467242 |pages=87–88}} In males, the corpus callosum is larger than in females.{{cite book |last=Kitterle |first=F. L. |title=Hemispheric communication: Mechanism and models |year=1995 |publisher=Lawrence Erlbaum Associates |location=Hillsadale, N.J. |isbn=978-0805811445}} However, the splenium and the isthmus subregions of the corpus callosum are larger in females. The genu subregion is larger in males. These subregions may serve as the basis for sex differences in language.{{cite book|last=Hines |first=Melissa |title=Brain gender |year=2004 |publisher=Oxford University Press |isbn=9780195188363 |pages=191–197}} However, a 1997 meta-study concluded that there is no relative size difference, and that the larger corpus callosum in males is due to generally larger brains in males on average; a small man and a large man would therefore have the same distinctions as the average man and the average woman.{{Cite web |title=Massive study reveals few differences between men's and women's brains |url=https://www.sciencedaily.com/releases/2021/03/210325115316.htm |access-date=2024-01-20 |website=ScienceDaily |language=en}}{{cite journal |doi=10.1016/S0149-7634(96)00049-8 |last1=Bishop |first1=K. |last2=Wahlsten |first2=D. |year=1997 |title=Sex Differences in the Human Corpus Callosum: Myth or Reality? |url=http://libres.uncg.edu/ir/uncg/f/D_Wahlsten_Sex_1997.pdf |journal=Neuroscience & Biobehavioral Reviews |volume=21 |issue=5 |pages=581–601 |pmid=9353793 |s2cid=9909395}}

In total and on average, females have a higher percentage of grey matter in comparison to males, and males a higher percentage of white matter.{{cite journal |last1=Marner |first1=L. |last2=Nyengaard |first2=J.R. |last3=Tang |first3=Y. |last4=Pakkenberg |first4=B. |year=2003 |title=Marked loss of myelinated nerve fibers in the human brain with age |journal=The Journal of Comparative Neurology |volume=462 |issue=2 |pages=144–52 |pmid=12794739 |doi=10.1002/cne.10714 |s2cid=35293796}}{{cite journal |last1=Gur |first1=Ruben C. |last2=Turetsky |first2=Bruce I. |last3=Matsui |first3=Mie |last4=Yan |first4=Michelle |last5=Bilker |first5=Warren |last6=Hughett |first6=Paul |last7=Gur |first7=Raquel E. |author-link7=Raquel Gur |date=15 May 1999 |title=Sex Differences in Brain Gray and White Matter in Healthy Young Adults: Correlations with Cognitive Performance |journal=The Journal of Neuroscience |volume=19 |issue=10 |pages=4065–4072 |doi=10.1523/JNEUROSCI.19-10-04065.1999 |pmc=6782697 |pmid=10234034}} However, some researchers maintain that as males have larger brains on average than females, when adjusted for total brain volume, the grey matter differences between sexes is small or nonexistent. Thus, the percentage of grey matter appears to be more related to brain size than it is to sex.{{cite journal |doi=10.1093/cercor/bhn052 |last1=Leonard |first1=C. M. |last2=Towler |first2=S. |last3=Welcome |first3=S. |last4=Halderman |first4=L. L. |last5=Otto |first5=R. Eckert |last6=Chiarello |first6=C. |last7=Chiarello |first7=C. |year=2008 |title=Size Matters: Cerebral Volume Influences Sex Differences in Neuroanatomy |journal=Cerebral Cortex |volume=18 |issue=12 |pages=2920–2931 |pmid=18440950 |pmc=2583156}}{{cite journal |doi=10.1097/00001756-200212030-00040 |last1=Luders |first1=E. |last2=Steinmetz |first2=H. |last3=Jancke |first3=L. |year=2002 |title=Brain size and grey matter volume in the healthy human brain |journal=NeuroReport |volume=13 |issue=17 |pages=2371–2374 |pmid=12488829}}

In 2005, Haier et al. reported that, compared with males, females show fewer grey matter areas associated with intelligence, but more white matter areas associated with intelligence. He concluded that "men and women apparently achieve similar IQ results with different brain regions, suggesting that there is no singular underlying neuroanatomical structure to general intelligence and that different types of brain designs may manifest equivalent intellectual performance."{{cite journal |last1=Haier |first1=Richard J. |last2=Jung |first2=Rex E. |last3=Yeo |first3=Ronald A. |last4=Head |first4=Kevin |last5=Alkire |first5=Michael T. |title=The neuroanatomy of general intelligence: sex matters |journal=NeuroImage |date=March 2005 |volume=25 |issue=1 |pages=320–327 |doi=10.1016/j.neuroimage.2004.11.019 |pmid=15734366 |s2cid=4127512}}

• {{cite press release |date=January 22, 2005 |title=Intelligence in men and women is a gray and white matter |website=ScienceDaily |url=https://www.sciencedaily.com/releases/2005/01/050121100142.htm}} Using brain mapping, it was shown that males have more than six times the amount of gray matter related to general intelligence than females, and females have nearly ten times the amount of white matter related to intelligence than males.

{{cite journal |last1=Haier |first1=R.J. |last2=Jung |first2=R.E. |last3=Yeo |first3=R.A. |last4=Head |first4=K. |last5=Alkire |first5=M.T. |title=Structural brain variation and general intelligence |journal=NeuroImage |volume=23 |issue=1 |pages=425–33 |date=September 2004 |pmid=15325390 |doi=10.1016/j.neuroimage.2004.04.025 |s2cid=29426973 |url=http://www.ucihs.uci.edu/pediatrics/faculty/neurology/haier/pdf/82.pdf}} They also report that the brain areas correlated with IQ differ between the sexes. In short, males and females apparently achieve similar IQ results with different brain regions. However, a 2019 study challenged the base assertions of articles such as Haier et al., finding there is no significant, consistent difference in grey and white matter between males and females.{{Cite journal |last1=Sanchis-Segura |first1=Carla |last2=Ibañez-Gual |first2=Maria Victoria |last3=Adrián-Ventura |first3=Jesús |last4=Aguirre |first4=Naiara |last5=Gómez-Cruz |first5=Álvaro Javier |last6=Avila |first6=César |last7=Forn |first7=Cristina |date=2019-07-01 |title=Sex differences in gray matter volume: how many and how large are they really? |journal=Biology of Sex Differences |volume=10 |issue=1 |pages=32 |doi=10.1186/s13293-019-0245-7 |doi-access=free |issn=2042-6410 |pmc=6604149 |pmid=31262342}}

The amygdala is the structure that responds to emotionally arousing information, respond to the environment, and reacts with stress. The male amygdala was believed to be proportionally larger than that in females, causing sex to be a determining factor in reactions to stress. However, this is not the case.{{Cite journal |last1=Marwha |first1=Dhruv |last2=Halari |first2=Meha |last3=Eliot |first3=Lise |date=2017 |title=Meta-analysis reveals a lack of sexual dimorphism in human amygdala volume |url=https://linkinghub.elsevier.com/retrieve/pii/S1053811916307431 |journal=NeuroImage |language=en |volume=147 |pages=282–294 |doi=10.1016/j.neuroimage.2016.12.021|pmid=27956206 |s2cid=3479632 |url-access=subscription }} The hippocampus, crucial for memory storage and spatial mapping of the physical environment, was likewise thought to be larger in females than in males.{{Cite journal |last1=Tan |first1=Anh |last2=Ma |first2=Wenli |last3=Vira |first3=Amit |last4=Marwha |first4=Dhruv |last5=Eliot |first5=Lise |date=2016 |title=The human hippocampus is not sexually-dimorphic: Meta-analysis of structural MRI volumes |url=https://linkinghub.elsevier.com/retrieve/pii/S1053811915007697 |journal=NeuroImage |language=en |volume=124 |issue=Pt A |pages=350–366 |doi=10.1016/j.neuroimage.2015.08.050|pmid=26334947 |s2cid=26316768 |url-access=subscription }}

A brain study done by the NIH showed that the females had greater volume in the prefrontal cortex, orbitofrontal cortex, superior temporal cortex, lateral parietal cortex, and insula, whereas males had greater volume in the ventral temporal and occipital regions.{{Cite web |date=2020-07-27 |title=Sex differences in brain anatomy |url=https://www.nih.gov/news-events/nih-research-matters/sex-differences-brain-anatomy |access-date=2023-03-27 |website=National Institutes of Health (NIH) |language=EN}}

{{See also|Sex differences in sensory systems}}

• Some studies have shown that females have a more sensitive sense of smell than males, both in the differentiation of odors and in the detection of slight or faint odors.
• Females have more pain receptors in the skin. That may contribute to the lower pain tolerance of females.{{cite web|url=https://www.sciencedaily.com/releases/2005/10/051025073319.htm |title=Study Reveals Reason Women Are More Sensitive To Pain Than Men |website=ScienceDaily |date=October 2005}} While most females expect to be less tolerant to pain, males expect to be more tolerant and therefore report agitation later. Due to variation across societies of gender roles, results of pain studies also vary depending on gender expectations.{{cite journal |vauthors=Defrin R, Shramm L, Eli I |title=Gender role expectations of pain is associated with pain tolerance limit but not with pain threshold |journal=Pain |volume=145 |issue=1–2 |pages=230–6 |date=September 2009 |pmid=19615821 |doi=10.1016/j.pain.2009.06.028 |s2cid=20186989}}
• Females also report a higher prevalence of many pain-related diseases and syndromes, particularly auto-immune diseases. In a 2005 study, Holdcroft and Beckley show a higher female prevalence of many conditions of the head and neck (e.g., migraine), limbs (e.g., carpal tunnel syndrome), internal organs (IBS), and more general conditions (multiple sclerosis).McMahon SB, M Koltzenburg, A Holdcroft, and K Beckley. Wall and Melzack's textbook of pain. Churchill Livingstone. 2005. (pp. 1181-1197) Fewer conditions show a male prevalence: e.g., cluster headache, gout.
• In addition to defined diseases and syndromes, many common "everyday" pains appear to overburden females rather than males. Therefore, studies consistently find that females report more severe pain, more frequent pain, longer-lasting pain, and wider-ranging pain than males.{{cite journal |last1=Kröner-Herwig |first1=Birgit |last2=Gaßmann |first2=Jennifer |last3=Tromsdorf |first3=Marie |last4=Zahrend |first4=Elfi |year=2012 |title=The effects of sex and gender role on responses to pressure pain |journal=GMS Psycho-Social-Medicine |volume=9 |pages=1–10 |pmc=3290921 |pmid=22400065 |doi=10.3205/psm000079}} For example, common painful conditions such as dysmenorrhea may predispose females to more widespread musculoskeletal pains.
• Females show higher performance levels on tests of verbal fluency. This may be because the female auditory cortex is denser than that of the male. This difference and other sensory differences like it could be because of the sex hormones that impact the fetal brain during development.{{cite journal |last1=Cahill |first1=Larry |year=2005 |title=His Brain, Her Brain |url=http://www.scientificamerican.com/article.cfm?id=his-brain-her-brain |url-status=dead |journal=Scientific American |volume=20 |issue=3 |pages=40–47 |doi=10.1038/scientificamericanmind0509-40 |archive-url=https://web.archive.org/web/20120317023332/http://www.scientificamerican.com/article.cfm?id=his-brain-her-brain |archive-date=17 March 2012|url-access=subscription }}; {{cite journal |last1=Alexander |first1=Gerianne M. |last2=Hines |first2=Melissa |year=2002 |title=Sex differences in response to children's toys in nonhuman primates (Cercopithecus aethiops sabaeus) |journal=Evolution and Human Behavior |volume=23 |issue=6 |pages=467–479 |doi=10.1016/s1090-5138(02)00107-1|bibcode=2002EHumB..23..467A }}

{{Expand section|date=May 2020}}

Strength and type of immune response differ in males and females. Generally speaking, females have a stronger immune response than males.{{Cite journal |last1=Klein |first1=Sabra L. |last2=Flanagan |first2=Katie L. |date=2016 |title=Sex differences in immune responses |url=https://www.nature.com/articles/nri.2016.90 |journal=Nature Reviews Immunology |language=en |volume=16 |issue=10 |pages=626–638 |doi=10.1038/nri.2016.90 |pmid=27546235 |issn=1474-1741|url-access=subscription }}{{Cite journal |last=Wilson |first=Clare |date=2023-02-04 |title=Are There Sex Differences in the Immune System? |journal=New Scientist |volume=257 |issue=3424 |pages=40 |doi=10.1016/S0262-4079(23)00214-2 |issn=0262-4079 |pmc=9897808 |pmid=36776694|bibcode=2023NewSc.257...40W }} This results in males having a higher morbidity and mortality from infectious diseases than females do, and lower rates of auto-immune diseases.{{cite journal|last1=Lotter |first1=Hanna |last2=Altfeld |first2=Marcus |date=1 March 2019 |title=Sex differences in immunity |journal=Seminars in Immunopathology |language=en |volume=41 |issue=2 |pages=133–135 |doi=10.1007/s00281-018-00728-x |pmid=30742253 |issn=1863-2300 |doi-access=free}}

• Females generally have a higher body fat percentage than males,{{ref|bodyfat}} whereas males generally have more muscle tissue mass.
• Females usually have lower blood pressure than males, and female's hearts beat faster, even when they are asleep.{{cite journal|last=Bren |first=Linda |title=Does Sex Make a Difference? |journal=FDA Consumer Magazine |date=July–August 2005 |url=https://www.fda.gov/fdac/features/2005/405_sex.html |url-status=dead |archive-url=https://web.archive.org/web/20090326023753/https://www.fda.gov/fdac/features/2005/405_sex.html |archive-date=26 March 2009}}
• Males and females have different levels of certain hormones. Males have a higher concentration of androgens while females have a higher concentration of estrogens.
• To date, wound healing studies have chiefly reported a female advantage in healing of dermal wounds.{{cite journal|last1=Ashcroft |first1=Gillian S. |last2=Dodsworth |first2=Joanne |last3=Boxtel |first3=Egon Van |last4=Tarnuzzer |first4=Roy W. |last5=Horan |first5=Michael A.|last6=Schultz|first6=Gregory S. |last7=Ferguson |first7=Mark W.J. |date=November 1997|title=Estrogen accelerates cutaneous wound healing associated with an increase in TGF-β1 levels|url=http://www.nature.com/articles/nm1197-1209 |journal=Nature Medicine |language=en |volume=3 |issue=11 |pages=1209–1215 |doi=10.1038/nm1197-1209 |pmid=9359694 |s2cid=23922583 |issn=1078-8956|url-access=subscription }}{{cite journal|last1=Ashcroft |first1=Gillian S. |last2=Mills |first2=Stuart J. |date=1 September 2002 |title=Androgen receptor–mediated inhibition of cutaneous wound healing |url= |journal=Journal of Clinical Investigation |language=en |volume=110 |issue=5 |pages=615–624 |doi=10.1172/JCI0215704 |pmid=12208862 |pmc=151108 |issn=0021-9738}}{{cite journal|last1=Jorgensen |first1=Lars Nannestad |last2=Sorensen |first2=Lars Tue |last3=Kallehave |first3=Finn |last4=Vange |first4=Jakob |last5=Gottrup |first5=Finn |date=March 2002 |title=Premenopausal women deposit more collagen than men during healing of an experimental wound |url=https://linkinghub.elsevier.com/retrieve/pii/S0039606002086221 |journal=Surgery |language=en |volume=131 |issue=3 |pages=338–343 |doi=10.1067/msy.2002.119986 |pmid=11894040|url-access=subscription }}{{cite journal|last1=Shimizu |first1=Tadamichi |last2=Nishihira |first2=Jun |last3=Watanabe |first3=Hirokazu |last4=Abe |first4=Riichiro |last5=Honda |first5=Ayumi |last6=Ishibashi |first6=Teruo |last7=Shimizu |first7=Hiroshi |date=2 April 2004 |title=Macrophage Migration Inhibitory Factor Is Induced by Thrombin and Factor Xa in Endothelial Cells |journal=Journal of Biological Chemistry |language=en |volume=279 |issue=14 |pages=13729–13737 |doi=10.1074/jbc.M400150200 |pmid=14736878 |s2cid=41653014 |issn=0021-9258 |doi-access=free}}{{cite journal|last1=Gilliver |first1=Stephen C. |last2=Ashworth |first2=Jason J. |last3=Ashcroft |first3=Gillian S. |date=January 2007 |title=The hormonal regulation of cutaneous wound healing |url=https://linkinghub.elsevier.com/retrieve/pii/S0738081X0600143X |journal=Clinics in Dermatology |language=en |volume=25 |issue=1 |pages=56–62 |doi=10.1016/j.clindermatol.2006.09.012 |pmid=17276202|url-access=subscription }} On the other hand, studies have found a male advantage in healing rates of mucosal wounds.{{cite journal|last=Engeland |first=Christopher G. |date=1 December 2006 |title=Mucosal Wound Healing: The Roles of Age and Sex |journal=Archives of Surgery |language=en |volume=141 |issue=12 |pages=1193–7; discussion 1198 |doi=10.1001/archsurg.141.12.1193 |pmid=17178961 |issn=0004-0010 |doi-access=}}{{cite journal|last1=Benediktsdóttir |first1=Ingibjörg S. |last2=Wenzel |first2=Ann |last3=Petersen |first3=Jens K. |last4=Hintze |first4=Hanne |date=April 2004 |title=Mandibular third molar removal: Risk indicators for extended operation time, postoperative pain, and complications |url=https://linkinghub.elsevier.com/retrieve/pii/S1079210403006383 |journal=Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology, and Endodontology |language=en |volume=97 |issue=4 |pages=438–446 |doi=10.1016/j.tripleo.2003.10.018 |pmid=15088029|url-access=subscription }} Thus, sex advantages in wound healing appear to be tissue specific.
• Adult males have approximately 5.2 million red blood cells per cubic millimeter of blood, whereas females have approximately 4.6 million.{{cite web|url=http://health.howstuffworks.com/blood1.htm |title=Howstuffworks "Red Blood Cells" |date=April 2000}}
• Females typically have more white blood cells (stored and circulating), more granulocytes, and B and T lymphocytes. Additionally, they produce more antibodies at a faster rate than males. Hence they develop fewer infectious diseases and succumb for shorter periods.
• Findings from a 2018 study revealed that there are several differences in cellular characteristics (e.g., cytoskeleton) of female and male cells.{{cite journal |doi=10.1021/acsnano.7b06212 |volume=12 |issue=3 |title=Effect of Cell Sex on Uptake of Nanoparticles: The Overlooked Factor at the Nanobio Interface |year=2018 |journal=ACS Nano |pages=2253–66 |last1=Serpooshan |first1=Vahid |last2=Sheibani |first2=Sara |last3=Pushparaj |first3=Pooja |last4=Wojcik |first4=Michal |last5=Jang |first5=Albert Y. |last6=Santoso |first6=Michelle R. |last7=Jang |first7=Joyce H. |last8=Huang |first8=Haina |last9=Safavi-Sohi |first9=Reihaneh |last10=Haghjoo |first10=Niloofar |last11=Nejadnik |first11=Hossein |last12=Aghaverdi |first12=Haniyeh |last13=Vali |first13=Hojatollah |last14=Kinsella |first14=Joseph Matthew |last15=Presley |first15=John |last16=Xu |first16=Ke |last17=Chung-Ming Yang |first17=Phillip |last18=Mahmoudi |first18=Morteza |pmid=29536733}}

Females live longer than males in most countries around the world. In Russia, however, the sex-associated gap has been increasing as male life expectancy declines.{{cite web|url=http://www.newtimes.ru/eng/detail.asp?art_id=1537 |title=A Country of Widows |archive-url=https://web.archive.org/web/20060415083231/http://www.newtimes.ru/eng/detail.asp?art_id=1537 |archive-date=15 April 2006 |first=Viktor |last=Perevedentsev |website=New Times |date=May 2006}}

The longer average life span of females can lead to skewed statistical results in regard to sex differences. For example, females are often seen to be at a higher risk of bone fracture due to osteoporosis. Although females do lose bone density faster than males after menopause, the data shows a larger disparity because there are more older females in the population.{{sfn|Birke|2001|pp=307–322}}

The gender gap in life expectancy suggests differences in the aging process between males and females. A key factor underlying aging is considered to be DNA damage, particularly DNA double-strand breaks, and the capability to repair these damages declines with age.{{cite journal | doi=10.18632/aging.203519 | title=Sex-specific differences in DNA double-strand break repair of cycling human lymphocytes during aging | date=2021 | last1=Rall-Scharpf | first1=Melanie | last2=Friedl | first2=Thomas W.P. | last3=Biechonski | first3=Shahar | last4=Denkinger | first4=Michael | last5=Milyavsky | first5=Michael | last6=Wiesmüller | first6=Lisa | journal=Aging | volume=13 | issue=17 | pages=21066–21089 | pmid=34506302 | pmc=8457596 }} Repair of DNA double-strand breaks is catalyzed by multiple pathways and expression of these repair pathways was found to be subject to changes upon aging. These age-related changes in the expression of double-strand break repair pathways were observed to be distinctly different in men and women.

Certain diseases and conditions are clearly sex-related in that they are caused by the same chromosomes that regulate sex differentiation. Some conditions are X-linked recessive, in that the gene is carried on the X chromosome. Genetic females (XX) will show symptoms of the disease only if both their X chromosomes are defective with a similar deficiency, whereas genetic males (XY) will show symptoms of the disease if their only X chromosome is defective. (A female may carry such a disease on one X chromosome but not show symptoms if the other X chromosome works sufficiently.) For this reason, such conditions are far more common in males than in females.

X-linked recessive disorders include:"X-linked recessive disorders." . GP notebook, n.d. Web. 4 Dec 2011. .

• Red-green colour blindness
• Haemophilia A (factor VIII)
• Haemophilia B (factor IX)
• Duchenne Muscular Dystrophy
• X-linked agammaglobulinaemia
• X-linked ichythyosis
• Becker muscular dystrophy
• Non-specific X-linked mental retardation

X-linked dominant disorders include:"X-linked dominant disorders." . GP notebook, n.d. Web. 4 Dec 2011. .

• Xg blood group
• Vitamin D resistant rickets
• Rett's syndrome
• Fragile X syndrome

There are diseases that are caused by a defective Y chromosome or a defective number of them.

The World Health Organization (WHO) has produced a number of reports on gender and health.{{Cite web |url=http://www.who.int/gender/documents/en/ |title=Gender, women, and health, Reports from WHO 2002–2005 |publisher=World Health Organization |archive-url=https://web.archive.org/web/20040102213427/http://www.who.int/gender/documents/en/ |archive-date=2 January 2004 |url-status=dead}} The following trends are shown:

• Overall rates of mental illness are similar for males and females. There is no significant sex difference in rates of schizophrenia and bipolar depression. Females are more likely to suffer from unipolar depression, anxiety, eating disorders, and post-traumatic stress disorder. Males are more likely to suffer from alcoholism and antisocial personality disorder, as well as developmental psychiatric disorders such as autism spectrum disorders and Tourette syndrome.
• Females are more likely to suffer from depression, due in part to their generally lower social status (e.g., higher rates of poverty), which is a powerful predictor for depression.{{Cite web |title=Women's increased risk of depression |url=https://www.mayoclinic.org/diseases-conditions/depression/in-depth/depression/art-20047725 |access-date=2024-01-20 |website=Mayo Clinic |language=en}}
• While males are more likely to suffer from alcoholism, females are more prone to addiction. This is because estrogen boosts the release of dopamine in brain regions important for regulating drug-seeking behavior, making women more vulnerable to dependence.{{Cite journal |last1=Quigley |first1=Jacqueline A. |last2=Logsdon |first2=Molly K. |last3=Turner |first3=Christopher A. |last4=Gonzalez |first4=Ivette |last5=Leonardo |first5=Noah |last6=Becker |first6=Jill B. |date=2021-04-01 |title=Sex differences in vulnerability to addiction |journal=Neuropharmacology |volume=187 |pages=108491 |doi=10.1016/j.neuropharm.2021.108491 |issn=0028-3908 |pmc=7979496 |pmid=33567305}}
• Schizophrenia does not show prevalence differences of significance among sexes, but there is a difference in the brain structures related. Females naturally have a higher orbitofrontal-to-amygdala ratio (OAR) than males, but not schizophrenic females (lower OAR). Males with schizophrenia however, have a higher orbitofrontal-to-amygdala ratio than that of healthy males.
• Before menopause, females are less likely to suffer from cardiovascular disease. However, for older men and postmenopausal women, this gap is much narrower as postmenopausal women are at higher risk of cardiovascular disease than premenopausal women.{{Cite journal |last1=Jousilahti |first1=Pekka |last2=Vartiainen |first2=Erkki |last3=Tuomilehto |first3=Jaakko |last4=Puska |first4=Pekka |date=1999-03-09 |title=Sex, Age, Cardiovascular Risk Factors, and Coronary Heart Disease: A Prospective Follow-Up Study of 14 786 Middle-Aged Men and Women in Finland |url=https://www.ahajournals.org/doi/10.1161/01.CIR.99.9.1165 |journal=Circulation |language=en |volume=99 |issue=9 |pages=1165–1172 |doi=10.1161/01.CIR.99.9.1165 |pmid=10069784 |issn=0009-7322|url-access=subscription }}{{Cite journal |last1=Ryczkowska |first1=Kamila |last2=Adach |first2=Weronika |last3=Janikowski |first3=Kamil |last4=Banach |first4=Maciej |last5=Bielecka-Dabrowa |first5=Agata |date=2022-12-10 |title=Menopause and women's cardiovascular health: is it really an obvious relationship? |journal=Archives of Medical Science |volume=19 |issue=2 |pages=458–466 |doi=10.5114/aoms/157308 |issn=1734-1922 |pmid=37034510|pmc=10074318 }}
• Overall, males are more likely to suffer from cancer, with much of this driven by lung cancer. In most countries, more men than women smoke, although this gap is narrowing especially among young women.{{Cite web |title=Gender Disparities in Health and Mortality |url=https://www.prb.org/resources/gender-disparities-in-health-and-mortality/ |access-date=2024-01-20 |website=PRB |language=en-US}}
• Females are more likely to be blind than males. The American Academy of Ophthalmology and The International Agency for the Prevention of Blindness note that this may be linked to higher life expectancy and age-related conditions, and that females are less likely to get timely treatments for conditions that lead to blindness, such as cataracts and trachoma.{{Cite web |date=2017-04-24 |title=Women Face Higher Risk of Blindness Than Men |url=https://www.aao.org/newsroom/news-releases/detail/women-face-higher-risk-of-blindness-than-men |access-date=2024-01-20 |website=American Academy of Ophthalmology |language=en}}{{Cite web |title=Gender |url=https://www.iapb.org/learn/vision-atlas/inequality-in-vision-loss/gender/ |access-date=2024-01-20 |website=The International Agency for the Prevention of Blindness |language=en-GB}}
• Females are more likely to suffer from osteoarthritis and osteoporosis. The density of bones depends upon the stresses that are put on them through exercise. Exercise and activity in childhood help to build up higher density bones. Although in Britain female's bones are less dense even before menopause, in some African societies, males and females are equally susceptible to osteoporosis.{{sfn|Birke|2001|p=316}}

Infectious disease prevalence varies - this is largely due to cultural and exposure factors. In particular the WHO notes that:

• Worldwide, more males than females are infected with HIV. The exception is sub-Saharan Africa, where more females than males are infected.
• Adult males are more likely to be diagnosed with tuberculosis.

Some other sex-related health differences include:

• Anterior cruciate ligament (ACL) injuries, especially in basketball, occur more often in females than in males.{{Cite web |date=2022-10-03 |title=ACL Tears in Female Athletes: Q&A with a Sports Medicine Expert |url=https://www.hopkinsmedicine.org/health/conditions-and-diseases/acl-injury-or-tear/acl-tears-in-female-athletes-qa-with-a-sports-medicine-expert |access-date=2024-01-20 |website=www.hopkinsmedicine.org |language=en}}
• From conception to death, but particularly before adulthood, females are generally less vulnerable than males to developmental difficulties and chronic illnesses.{{cite journal |last1=Marlow |first1=Neil |last2=Wolke |first2=Dieter |last3=Bracewell |first3=Melanie A. |last4=Samara |first4=Muthanna |last5=Epicure Study |first5=Group |title=Neurologic and Developmental Disability at Six Years of Age after Extremely Preterm Birth |journal=New England Journal of Medicine |volume=352 |issue=1 |pmid=15635108 |doi=10.1056/NEJMoa041367 |date=January 2005 |pages=9–19|doi-access=free }}{{cite journal |last1=Kraemer |first1=S. |title=The fragile male: Male zygotes are often formed at suboptimal times in fertile cycle |journal=British Medical Journal |volume=321 |issue=7276 |pages=1609–1612 |year=2000 |pmid=11124200 |pmc=1119807 |doi=10.1136/bmj.321.7276.1609}} This could be due to females having two x chromosomes instead of just one,{{cite news |first=Nicholas |last=Wade |title=Pas De Deux of Sexuality is Written in the Genes |work=The New York Times |date=10 April 2007 |url=https://www.nytimes.com/2007/04/10/health/10gene.html?_r=1}} or in the reduced exposure to testosterone.{{cite book |first=Richard |last=Bribiescas |year=2008 |title=Men: Evolutionary and Life History |isbn=978-0-674-03034-3 |publisher=Harvard University Press}}

• Sex ratio
• Sex differences in psychology
• Gender-based medicine
• Genetics of sex
• Gender differences in coping
• Sexual dimorphism
• Sex differentiation
• Sex and intelligence
• Virilization
• List of homologues of the human reproductive system
• Man flu

{{Reflist|30em}}

• {{cite book |last=Birke |first=Lydia |title=The Gender and Science Reader |editor-first1=Muriel |editor-last1=Lederman |editor-first2=Ingrid |editor-last2=Bartsch |location=New York |publisher=Routledge |date=2001}}
• {{cite book |last=Merry |first=Clare V. |chapter-url=https://books.google.com/books?id=mKHRUUQbt34C&pg=PA48 |title=Mind - Primary Cause of Human Evolution |chapter=Pelvic Shape |publisher=Trafford Publishing |year=2005 |isbn=1-4120-5457-5}}
• {{cite book |last1=Schuenke |first1=Michael |title=Thieme Atlas of Anatomy: General Anatomy and Musculoskeletal System |publisher=Thieme |year=2006 |isbn=978-1-58890-419-5 |first2=Erik |last2=Schulte |first3=Udo |last3=Schumacher}}

• {{cite journal |last=Geary |first=D.C. |author-link=David C. Geary |title=Sex differences in social behavior and cognition: utility of sexual selection for hypothesis generation |journal=Hormones and Behavior |volume=49 |issue=3 |pages=273–5 |date=March 2006 |pmid=16137691 |doi=10.1016/j.yhbeh.2005.07.014 |s2cid=4946571}} [http://web.missouri.edu/~gearyd/files/Geary%20%5B2006,%20Hormones%20&%20Beh%5D.pdf Full text] {{Webarchive|url=https://web.archive.org/web/20090912102149/http://web.missouri.edu/~gearyd/files/Geary%20%5B2006%2C%20Hormones%20%26%20Beh%5D.pdf |date=2009-09-12 }}

• {{cite journal |last=Brin |first=David |author-link=David Brin |title=Neoteny and Two-Way Sexual Selection in Human Evolution: A Paleo-Anthropological Speculation on the Origins of Secondary-Sexual Traits, Male Nurturing and the Child as a Sexual Image |journal=Journal of Social and Evolutionary Systems |volume=18 |pages=257–76 |year=1996 |url=http://www.davidbrin.com/neotenyarticle1.html |doi=10.1016/1061-7361(95)90006-3 |issue=3 |url-status=dead |archive-url=https://web.archive.org/web/20071208223505/http://www.davidbrin.com/neotenyarticle1.html |archive-date=2007-12-08|url-access=subscription }}

{{Sex}}

{{Human group differences}}

{{Authority control}}

{{DEFAULTSORT:Sex Differences In Humans}}

Physiology

Category:Social inequality