How did sexism in the Victorian era affect Darwin’s theories – new research

Sex is a biologically expensive business. Finding a suitable mate takes time and energy. Offspring is also a huge investment of resources. But sex offers a rewarding possibility: children are fitter than their parents thanks to new and “better” combinations of genes. Darwin realized that many animal species choose their mates carefully.

However, there is an innate biological variance. The eggs are relatively few in number – a big and expensive investment – while the sperm are small and abundant. And fetuses often need more investment in or out of the body. Since the biggest investment tends to fall on the females, it is often the more selective sex (while males compete for selection).

But according to a new research paper published in Science, Charles Darwin’s paternalistic view of the world led him to reject female agency and mate choice in humans.

He also downplayed the role of female variation in other animal species, assuming that they were somewhat homogeneous, and always made similar decisions. And he thought there was a huge disparity between males who struggled to attract females’ attention by flaunting an astonishing array of skills and beauty. This kept the focus on the dynamics of the male dominance hierarchy, and sexual ornamentation and difference as drivers of sexual selection, even if females sometimes did choose.

But do Darwin’s ideas about sexual selection survive today?

The tubular male carries the eggs until they hatch.
Francois Lippert / Flickr

Complicated choices

When animals choose a mate, their appearance, sound, and smell can all be accurate clues to a prospective mate’s ability to survive. For example, large deer antlers are a good indicator of fighting ability, dominance, and general fitness. But many other traits can be selected because they are otherwise notable and attractive, but may be poor evidence of overall genetic quality, or even misleading.

Females may evolve to select mates whose offspring are less likely to survive with them, provided there are more offspring such as barter. In some fish species, for example, male attractiveness is linked to genes that can reduce their survival. So females face a dilemma: they mate with a more attractive male and produce some very attractive but less powerful offspring, or they mate with a less attractive male to maximize the survival of those offspring. What strategy will produce the most grandchildren?

So females may choose traits in males that seem to have no other effect on their ability to survive. The peacock’s tail is a hindrance in most other aspects of his life – an impediment to escape and escape from predators – except for the attraction of the female. However, it may also be true that a male’s ability to manage such a burden is in itself a sign of overall genetic quality and rigor.

Picture of a statue of Charles Darwin, Museum of Natural History.  London.
Darwin, Museum of Natural History. London.
stock struggle

Females are not always the ones to choose. In the tubes, the males invest heavily by carrying the fertilized eggs until they hatch, and it is the females that compete with each other in order to secure the male’s attention.

Optimal choice of partner is not the same for all individuals, or for all times in their development. For example, younger satin bowerbirds are afraid of the displays of more active males, while older females find these more attractive. And many fish are sequential hermaphrodites, and sex—and thus their mating choices—change as they age.

So research since Darwin reveals that mate selection is a much more complex process than he might have assumed, and is governed by difference in both sexes.

Was Darwin a sexist?

So, is Darwin’s accusation of sexism really true, and does this overshadow his knowledge? There is certainly some evidence that Darwin underestimated difference, strategy, and even promiscuity in most female animals.

For example, Darwin – perhaps a consequence of prevailing wisdom – placed little emphasis on the mechanisms of sexual selection at work after mating. Female birds and mammals may choose to mate with multiple males, and their sperm can compete to fertilize one or more eggs within the reproductive system.

Cats, dogs, and other animals can have offspring with multiple fathers (it’s gloriously called “hetero-paternal fertilization” – although it sounds really awful!). There is even some suggestion that the human penis – being thicker than our closest primate relative – is an adaptation to displace sperm from physically competing males. Such earthy speculations were anathema to Darwin’s sensibilities.

Female blue tits often mate with multiple males in order to ensure their protection and support – a somewhat manipulative strategy when the paternity of potential fathers is uncertain. All of this challenges Darwin’s assumption that females are relatively passive and non-strategic.

When males make a greater investment, they become more active in choosing a partner. male (not female) poison dart frogs (Dendrobates auratus) protect her young, thus attracting several females who compete to lay eggs for her for fertilization. Many bird species enjoy bi-parental care, and therefore a richer diversity of mating systems.

Poisonous frog picture.
Dendrobates auratus, a poisonous dart frog.
Brian Gratwicke / Flickr

Inevitably, Darwin’s worldview was shaped by the culture of his time, and his personal writings make it particularly difficult to mount a solid defense. In a letter from 1882, he wrote: “I certainly believe that women, though generally superior to men [sic] Moral qualities are intellectually inferior; And it seems to me that there is great difficulty in the laws of inheritance… in becoming an intellectual peer of a human being.”

He also discussed the relative merits of marriage, noting the following: “A home, and someone who takes care of the house – the magic of music and feminine chat. – These things are good for human health. – But a terrible waste of time.”

Not surprisingly, there is much that Darwin did not fully understand. Darwin—like Albert Einstein, H.G. Wells, and Edgar Allan Poe—married his first cousin Emma Wedgwood. Ironically, nothing is known about genetics and the mechanisms by which relatives are likely to have offspring with certain genetic diseases. Interestingly, our closest relative in the tree of life, the chimpanzee, naturally circumvents this problem, because females choose mates with whom they relate more distantly than the average man in the available pool.

Chimpanzee picture.
Female chimpanzees make good choices.
Phenix / PixaHive, CC BY

Although omitted, Darwin’s understanding was radically more advanced than anything that had preceded it. When combined with later understanding of genetics and genetics, Darwin’s writings still form the bedrock of all modern evolutionary biology.

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