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I've always thought that "women are weaker1 than men in general" was a biological fact (supposedly stemming/evolving from the social structure of prehistoric humans)

Is there any reputable research done which demonstrates (or disproves) that the average woman has the same strength as the average man?

1 In this post, "weaker" means "physically weaker", and refers only to cis women (not transgender women)

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    Note that nearly every woman has a stronger myometrium (muscle layer of the uterus) than nearly any man has. Admittedly, video games in which a character prevails by using the myometrium are, um, rare.
    – minopret
    Mar 17, 2013 at 15:13
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    Do you want to control for height, weight, and/or other measures of physical size, in case women are on average smaller?
    – ChrisW
    Dec 18, 2013 at 17:27
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    So, should we argue against separate men's and women's races in the Olympics?
    – GEdgar
    Aug 27, 2015 at 21:44
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    I think if you look at the effects of hormone replacement therapy in both types of transgender people (FtM and MtF), it becomes pretty clear that muscle mass and overall strength changes a lot by just changing hormonal balance to those of the target biological sex. This effect wouldn't happen if this strength gap was merely cultural.
    – T. Sar
    Jul 5, 2017 at 11:27
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    The original source of this claim is criticizing the notion that "women, as a group, need to be sheltered, protected, and taken care of by men". The term "weaker" used in the next sentence seems to be a reference back to that idea, attempting to refer to it in a single word. So, the original source really doesn't appear to be talking about physical strength. Seems like the question's worth keeping as-is as it's already got a few answers, though it seems unreasonable to interpret the claim as having been made by the cited source.
    – Nat
    Sep 7, 2017 at 1:20

3 Answers 3

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+50

What do we mean by weaker, or by stronger?

"Women really are stronger than men, according to study"

Is the title of a BBC article which says

A recent academic study has shown that under extreme conditions such as famines, epidemics and enslavement, women are able to survive for longer than men.

Across modern populations, women outlive men in almost all instances

The study says this

Abstract

Women in almost all modern populations live longer than men. Research to date provides evidence for both biological and social factors influencing this gender gap. Conditions when both men and women experience extremely high levels of mortality risk are unexplored sources of information. We investigate the survival of both sexes in seven populations under extreme conditions from famines, epidemics, and slavery. Women survived better than men: In all populations, they had lower mortality across almost all ages, and, with the exception of one slave population, they lived longer on average than men. Gender differences in infant mortality contributed the most to the gender gap in life expectancy, indicating that newborn girls were able to survive extreme mortality hazards better than newborn boys. Our results confirm the ubiquity of a female survival advantage even when mortality is extraordinarily high. The hypothesis that the survival advantage of women has fundamental biological underpinnings is supported by the fact that under very harsh conditions females survive better than males even at infant ages when behavioral and social differences may be minimal or favor males. Our findings also indicate that the female advantage differs across environments and is modulated by social factors.

Now this type of strength might not be what the question refers to. Perhaps some people might prefer to label this attribute as (biological) toughness rather than strength?

At the very least, we should be aware that when one person says group A is stronger than group B or another person disputes that statement, we should consider carefully what type of strength is being referred to.


Types of Strength/Weakness

The question quotes a video as saying

The belief that women are somehow a naturally weaker gender ...

but it may be that the author of the video is, perhaps in part, perhaps mostly, referring to other kinds of historically perceived weakness: emotional and intellectual.

This answer doesn't address that but we probably shouldn't assume the author was only referring to muscle size and not to strengths like toughness, determination, perseverance and so on.

We can put the above concerns to one side and consider muscular strength.


Sexual dimorphism in primates

Age and gender comparisons of muscle strength in 654 women and men aged 20–93 yr in the Journal of Applied Physiology contains this graph

Regression analysis of age and gender-related differences
Fig. 1. Regression analysis of age- and gender-related differences in concentric (Con; A) and eccentric (Ecc; B) peak torque of knee extensors at slow (0.52 rad/s) velocity. Both Con and Ecc peak torque declined significantly (all P < 0.001) for men (r 2 = 0.30 for Con and 0.19 for Ecc) and women (r 2 = 0.28 for Con and 0.11 for Ecc).

We can see that many women are stronger than many men (i.e. there is considerable overlap in the data) but that the average strength for women is lower.

Sexual dimorphism in Humans is relatively small according to anthropologist Clark Spencer Larsen of Ohio State University writing in PNAS

Humans today display relatively limited sexual dimorphism (≈15%), whereas some of the other hominoids (gorillas and orangutans) are highly dimorphic (>50%)


Causation

According to Kirchengast S.

Although sexual size dimorphism has a clear evolutionary basis and is caused by genetic and hormonal factors, socio-cultural factors such as gender role in society and gender typical workload influence the degree of sexual size dimorphism too.

So some of the differences we perceive may be the result of cultural forces of the sort which change over time and from place to place.


When is using averages (mean or median) useful and when inappropriate

The question asks about the strength of the average woman vs the average male but in most situations (e.g. interviewing job candidates) we are not interacting with the average person we are more likely interacting with a person whose physical characteristics may be anywhere on the spectrum above. If you select two people at random, one male, one female, there is a significant probability (less than .5 but far higher than 0) that the female is stronger than the male. Focussing on small differences in overall averages for a large population is inappropriate for most situations which involve only a few individuals.

It would be bizarre to say to a candidate, you are strong enough to do this job but you are ineligible because you are a member of a group whose average strength is lower than the average of some other group. However this is exactly the sort of discrimination that has occurred in the past and that is part of the context for the video which stimulated the question above.

We should note that the quotation in the question doesn't use the word "average".


Social implications

It may be that the video referenced in the question is concerned whether this perception (true or not) contributes to an unreasonable bias against one part of our population.

The better question may be what do we do with this information. David Haye may be stronger than Stephen Hawking. Should we skew society to benefit people with large muscles at the expense of the others?

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    Skeletal muscle mass is on average significantly greater in men whether upper-body, lower-body, or total, but the difference for the upper body is significantly greater than the difference for the lower body. ncbi.nlm.nih.gov/pubmed/10904038 I wondered why all the female archer characters and realized that archery keeps them out of arm's reach.
    – minopret
    Mar 17, 2013 at 15:24
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    Cultural bias might be the cause when the average houswife is weaker than the average man due to "physical strength being dicouraged" but it's not a factor in sports, especially at the best of the best (world champions, record holders, etc.) where men have a clear advantage.
    – vsz
    Mar 18, 2013 at 7:15
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    This answer crucially does not answer the question, namely whether the cause of this difference is cultural rather than natural. Mar 18, 2013 at 10:54
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    Konrad, OP didn't ask that question.
    – Publius
    Mar 20, 2013 at 6:58
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    The second portion of your answer doesn't seem relevant to the question, and is mostly unreferenced speculative and apologetic opinion. The question is about averages, not potential and can trivially be answered empirically by your first portion.
    – Kit Sunde
    Dec 19, 2013 at 7:34
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Here is one clue. Visit the IAAF's page of athletic records and compare the men's and women's, category by category.

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    The claim in the Q is much more general. It is often a mistake to argue that what holds true for a very small specialised group also holds for a very much larger general group. Mar 18, 2013 at 9:58
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    The generations of teenage boys around the world who have run miles faster than 4:12 hardly constitute a small, specialized group. Also the women who have not done this is large: it consists of all women.
    – Kaz
    Mar 20, 2013 at 16:48
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    @DjangoReinhardt The point is that unremarkable male athletes not yet in their physical prime beat world records made by remarkable, rare women.
    – Kaz
    Dec 18, 2013 at 16:09
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    In general, while it raises some problems of its own (applying the specific to the general). That is a problem with all statistics. And I would argue this is in fact the best way to go about answering this question. When answering the question cultural or genetic, it is important to control for "drive". Women in general being told not to train at running fast, lifting huge amounts, etc. So we pick two groups of people with the exact same culture and drive, male and female professional athletes (people with the same drive to be the best, lift the most, run the fastest, train the most).
    – Jonathon
    Aug 1, 2014 at 17:11
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    What he posted is just an example, but I believe that if you look at sports results in general, you will get a similar outcome for most disciplines, even for team sports.
    – clabacchio
    Jul 6, 2017 at 13:06
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Grip Strength

When testing grip strength, a median young adult man is stronger than about 98%+ of young adult women. Even the top fraction of female athletes as a population are only slightly stronger than median young men.

Hand-grip strength of young men, women and highly trained female athletes, Eur J Appl Physiol (2007) 99:415–421, DOI: 10.1007/s00421-006-0351-1

grip strength data

Muscle Mass

Men also have much greater average total muscle mass.

Men had significantly (P < 0.001) more SM in comparison to women in both absolute terms (33.0 vs. 21.0 kg) and relative to body mass (38.4 vs. 30.6%). The gender differences were greater in the upper (40%) than lower (33%) body (P < 0.01).

total muscle

Jump Distance

long jump

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    This is for one very narrow definition of "weaker", and it appears that she didn't mean it that way when she made the statement. In the context of the video, how is grip strength important to the argument being made?
    – user18902
    Sep 4, 2017 at 12:16
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    Are you claiming she doesn't mean physically weaker, as in having less muscle mass and/or having weaker muscles? Grip strength is easily measured and easily compared and is hard to argue with much like other simple measures like height.
    – Murphy
    Sep 4, 2017 at 12:22
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    I'm saying that grid strength is a very specific measurement and this isn't Top Trumps.
    – user18902
    Sep 4, 2017 at 13:57
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    @ゼーロ The qestion is about physical strength/weakness. I'm merely using the dictionary definition. "the physical energy that someone has to lift or move things", You kinda have to bend over backwards to find inventive definitions such that the group with more muscle and stronger muscle don't count as having more physical strength.
    – Murphy
    Sep 4, 2017 at 18:07
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    @ゼーロ - Don't think that's a fair criticism on your part. You clearly take issue with the method of assessing "strength." To go by the video is not fair, because OP clearly states that the video only spurred the related posted question.They mean, specifically "physical strength" (see the end-note). Instead of saying "nope, not good enough," over and over, why aren't you offering the type of measurement that would be more relevant and accurate as a measurement of physical strength? You seem to feel there is an objective, universally accepted, non-arbitrary way to measure. Tell us what it is. Sep 6, 2017 at 18:59

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