Video summary
The central argument presented in this discussion challenges two common misconceptions regarding human sex differences: the belief that they are entirely cultural and non-existent, versus the tendency to exaggerate their magnitude. The speaker contends that while people often swing between these extremes, the reality lies on a narrow tightrope where evolved biological factors play a significant role alongside culture. A primary example of this is sexual orientation; despite being taken for granted by many, it represents one of the largest psychological sex differences in humans, with the vast majority of men interested primarily in women and vice versa for women. This massive difference demonstrates that natural selection can create substantial disparities within our species, even though most other mammalian sex differences are relatively modest compared to this specific trait. Beyond orientation, several other significant evolved differences are highlighted, including a medium-sized preference for sexual novelty among men versus women, a larger desire for casual sex in men, and distinct patterns of aggression where face-to-face violence is more prevalent in males. Perhaps the most profound psychological divergence discussed involves jealousy, which serves as a mechanism to protect pair bonds that were adaptive for raising offspring. While both sexes experience jealousy to safeguard their relationship, the specific triggers differ fundamentally due to evolutionary pressures regarding reproductive investment. Men are generally more distressed by sexual infidelity because of paternity uncertainty; since men cannot be biologically certain if a child is theirs without genetic testing in an ancestral context, investing resources into another man's offspring would waste those genes on non-biological descendants. In contrast, women prioritize emotional infidelity over sexual infidelity due to the catastrophic fitness costs associated with losing their partner's investment and care. If a woman's mate forms an emotional attachment to someone else, he is likely to abandon her and the child she bears, leaving her solely responsible for rearing offspring alone or delaying future reproduction until resources allow. This potential loss of paternal support poses a greater threat to maternal fitness than sexual infidelity itself, which does not necessarily result in the abandonment of the pair bond or the cessation of resource provision. Consequently, women have evolved a psychology that is more sensitive to emotional betrayal as it directly threatens their ability to successfully raise children and recover reproductive capacity. The discussion concludes by emphasizing how these distinct evolutionary rationales shape modern relationship dynamics without negating cultural influences entirely. The speaker notes that while we often overlook the sheer magnitude of differences like sexual orientation because they seem obvious, acknowledging them is crucial for understanding human psychology accurately. By recognizing that sex differences in jealousy are rooted in specific reproductive strategies—men guarding against raising another man's children and women guarding against losing their primary caregiver—we gain a clearer picture of how natural selection has sculpted our behaviors. Ultimately, the goal is to avoid falling into the trap of either denying these innate pushes or overstating them as universal absolutes, instead appreciating that modest but significant biological differences exist within mammals like humans alongside cultural variations.
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what do you think most people get wrong
when it comes to understanding sex
differences uh I think that that it's a
long list of
things um I'm working on a new book
actually and it's going to be focused on
sex differences hell yeah and I think so
okay so the two big things I think that
people get wrong um and the one that
probably people are going to be
expecting me to say and that I do say in
this new book um is that often think
that there are no sex differences or
that there are no um that there's no
innate push toward sex differences that
it's to the extent they exist at all
they come almost solely from culture and
I think that's one big mistake but I do
also think people make the opposite
mistake as well so there's also a
tendency to exaggerate the magnitude of
human sex differences uh I think both of
them are mistakes that people fall into
I think these days probably they more
often fall into um the first mistake the
minimizing and denying um mistake but
people do make both and I think both um
potentially cause
problems is it
a uh narrow tight rope to walk along to
actually get the amount of sex
differences right is it I think it is I
think it is very it is difficult because
I think people it's just very easy to to
swing to one extreme or the other um and
then if you okay if it's just sort of
started opening the door okay there are
some evolved sex differences and then I
think we may be quite easily spin to the
extreme with think thinking that they're
massive and that they're huge and in
some species they are um but I think
that um where as mammals go we have
relatively modest sex differences and
actually that's another thing I think
that the alien would be puzzled by he
would say okay we got these sex
differences in this this weird species
um but they belong to the big group
called mammals and in a lot of mammals
that the differences are much
larger what are your favorite
psychological sex differences in humans
um let me think okay so let me start
well the one I think is the biggest one
the single biggest um psychological sex
difference I suppose you can guess what
it might be desire for sexual
novelty that is that's usually about a
medium effect size um so about 0 five
maybe a bit bigger the one I'm picking
of is much much bigger than that [ __ ] uh
I I I give up tell me it's um it's one
that as soon as I say it you'll you'll
recognize it and you'll recognize that
it's huge I think we take it's so so
obvious to us that we take it for
granted and don't think of it um it's
the fact that the vast majority of men
are primarily interest sexually
interested in women and the vast
majority of women are primarily sexually
interested in men so it's interesting
that's that is a massive difference and
that does show that natural selection
can create huge sex differences in our
species and that most of the time it
creates sex differences that are that
are nowhere near that magnitude um it's
interesting though if you look at um
summaries of
sex differences and evolved sex
differences very often that one's just
left out and I just think it's just
because we take it for granted so much
that that's the case that we don't even
really think of it when when we're
listing them that's like the physics of
sex yeah yeah yeah yeah yeah exactly um
and there's a clear there's a clear
evolutionary rationale of course for it
as well um other ones on that list uh
would be the desire for sexual variety
like I said it's iMed ium sex difference
uh the desire for casual sex is a large
sex difference that's one that one's
actually larger usually than uh the
desire for sexual variety um sex
differences and aggression face Toof
face aggression and and violence in
particular that's another big one uh sex
differences in Parental
inclinations uh would be
another yeah it's
interesting the oh what's the one in
tell me about jealousy
uh sex difference in jealousy this isn't
this isn't a huge one but that is the
fact that um most uh so so men in
general uh on average are more upset
than women about sexual infidelity so if
their partner gets so so if you if you
ask people okay so imagine your partner
you're in love with your partner your
partner gets involved with somebody else
which would upset you more would would
you be more upset if they had sex with
somebody else or would you be more upset
if they got close to someone else kind
of fell in love with somebody else um
and obviously both of those things are
upsetting to most people but more men
than women say that the sexual
infidelity would be more upsetting to
them and more women than men say the
opposite they say that the emotional
infidelity would be more upsetting to
them yeah well I mean how many times has
there been some on Street interview I I
even remember this from back in school I
think about would you rather that your
girlfriend kissed someone else or told
you that they were in love with someone
else or whatever and just this asymmetry
in terms of what it is that we're
jealous about so can you run through can
you go a layer deeper and talk about how
those two types of jealousy are more and
less
adaptive yep um they we start with the
the commonality though so just the I
think the main function of jealousy for
both sexes it's part of our pair bonding
psychology so we we fall in love with
each other but we also had jealousy and
I think for both sexes the function the
main function of that is to protect the
peir
bond um peir Bonds were adaptive for us
in the past as a a setting for um having
kids and rearing kids and so we've
evolved a psychology to kind of protect
them uh the differen is though the main
difference um for men compared to women
is is paternity uncertainty so David bus
has a great way of putting this he says
there's never in the history of the
world been uh a case where you have a
woman who gives birth to a kid and then
thinks is this my kid
or is there some other woman's kid I
don't know um whereas for men if their
partner gives birth it's almost
certainly their kid but there is a
possibility that's not their kid and any
uh any guy that ended up investing in a
kid that wasn't his own biological kid
um the all the paternal effort that he
puts into that kid he's putting it in
effect into the genes of another guy and
so any any trait that would come along
that decrease the chances that that
would happen that trait would have a
good chance of being selected and
jealousy I think is is one of those um
so the kind of jealousy that makes the
guy keep a kind of wey eye on his
partner and on the good-looking next
door neighbor and to take action if they
start you know the guy at work maybe you
know she keeps talking about that guy at
work uh he starts getting a bit worried
about that maybe takes action to try to
uh make sure nothing happens maybe maybe
he's a bit more attentive maybe he you
know handles it in in nastier way but
because paternity uncertainty is the
main issue for guys
um well well paternity uncertainty is
facilitated by by sex not just falling
in love but but sex the sex sex act
itself itself is what um leads to
somebody having somebody else's care
right so um that's why that's the
rationale evolutionary rationale for why
guys are particularly focused on that uh
with women on the other hand um
emotional infidelity it's like this is a
big deal obviously it's a big deal to
people um a woman doesn't want her
partner sleeping with somebody else um
and she's going to be upset about that
and it's a common cause of the end of
relationships but evolutionarily
speaking it doesn't have quite the
catastrophic consequences that it does
for for guys um what can do though is if
if she has a nice peir on and they have
a kid and I'm thinking sort of
ancestrally more you have um this
investing dad um if he would have fallen
in love with someone else then that
would increase the chances that he's
actually just going to split up the pair
bond and go with somebody else uh and
that would make it a lot harder for her
to raise the kid it would uh ancestrally
increase the chances that the kid
wouldn't make it for a start but also it
just increase the burden on her so it
might be longer before she can have her
next kid it's this is going to be a big
hit to her Fitness uh and so and a
bigger head than if he just sleeps with
somebody else so that's the evolutionary
rationale for why she might be more
focused on uh love and Fidelity as
opposed to sex and Fidelity sexual and
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