By Mark Leary, Ph.D., Duke University
The changes in mating through evolution have left considerable impacts on today’s partner selection criteria. Women are pickier than men and have more criteria for an ideal partner because biologically, women have constraints that men do not. They also have to invest much more. Read on to find out how these conditions affected the genes that passed on to us.

Evolution works on the basis of reproductive success. Thus, current species carry genes from successful reproducers, both male and female. In humans, women that chose a partner with access to more resources were more successful in supporting their children to survive. At the same time, men only needed a woman who is young enough to reproduce, and they could father many children at the same time. This means that the number of males in our ancestors is fewer than females.
This is a transcript from the video series Understanding the Mysteries of Human Behavior. Watch it now, Wondrium.
Reproductive Dispensability
Men are more dispensable than women, in terms of reproduction, which means not as many men are needed for reproduction, as women. Each woman can have one child at a time, and the biological investment in each child is incomparably higher than the man. Thus, the women who chose partners more carefully and went for mates with better social status, power, and resources, invested in the right place.

Genes of more careful women passed down to the next generations, while those who chose weaker males did not succeed in reproduction and became extinct. However, not all males met the requirements for fathering their children, and they had no reproductive constraint. Hence, one competent male fathered many children with many females due to higher reproductive dispensability.
For example, an alpha male mates with all the females of the group, while the other males might never mate or might father a few children only. Thus, men could have many more children than a woman, but they needed to be competent enough for that.
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Male and Female Ancestors
DNA evidence suggests that only about one-third of our ancestors were men. Even though each child had one mother and one father, many shared the same father due to that male’s better status and resources. Thus, many people might share the same male ancestor but different female ones.
If we could draw everybody’s family trees going back about four million years, there would be only half as many individual men on the tree as women. Most women reproduced apart from the rare cases where they could not, due to biological reasons. In the case of men, almost all of them could biologically reproduce, but not all got picked for mating.
In other words, most women who ever lived had descendants, but many men did not. This obviously means that monogamy was not a popular thing with our ancestors. Why is it today?
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Monogamy in Today’s World
Most modern cultures insist on monogamy nowadays. This could lead to a more even balance in the number of male and female ancestors of future generations. However, anthropologists and biologists assume that polygamy was common in the past, which refers to males’ higher evolutionary expandability, and results in some psychological differences.
Monogamy gives less competent males a higher chance of finding a partner, only if they can make themselves more competent and gain enough resources. This is not that different from the way it was before.
Difficulties of Finding a Partner for Men
Since men were more available for mating, they always had to fight to win a woman’s attention. Psychologist Roy Baumeister explains how this has made men seek recognition through accumulating land and wealth, military exploits, politics, exploration, and similar achievements in ways that most women have not.

Women prefer men with higher ambition and resources because ambition shows that they will probably gain more resources in the future. Mating through evolution has taught males that they should always gain enough resources to attract females; otherwise they will not reproduce.
Today, most men are descendants of males that made some special effort to prove themselves. Thus, risk-taking genes survived and passed on to the next generations, making men more willing to take risks to prove themselves.
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Competitiveness in Men
The surviving genes can explain why men try so hard to out-do everyone and gain as much power as possible, even in the smallest areas. Women do not have this relentless competitive urge to the same degree because it did not provide the same reproductive benefits for them.
This does not mean that women cannot do the same, but they were usually not as interested as men in showing off and winning everything. They were the ones who could reproduce with not much effort in finding mates, with no need to develop competitive tendencies.
Common Questions about Mating through Evolution
Women do not mind younger partners, but rules of mating through evolution have shown them that men with access to more resources are better options to produce offspring that survive.
In the history of mating through evolution, men that tended to mate with younger women had higher chances of producing offspring because women have a limited number of fertile years.
Females are more choosy as they want a more competent male to reproduce with. Males, as a result, always had to try and show females that they are better choices for mating. So, women always had a wider range of choices in mating through evolution, and almost never needed to prove anything.
No, results of mating through evolution show that most of our ancestors were females. A male could father many children at the same time, and a female wanted a competent and strong male. Thus, the alpha males got to reproduce with various females, while some males never reproduced.