Women with significantly less body hair than their male counterparts have an evolutionary advantage. Mal Jones, Cardiff
Send your questions to nq@theguardian.com
Readers respond
Everything gets more tangled and closer to the ground as you age. We would all end up looking like shagpile carpets if we lived long enough. Lafferty
The question is a bit misleading in that it misunderstands evolution. Some human traits do not confer evolutionary advantages. Some traits are simply the result of another trait, like excess testosterone in hair. IngridCZ
This could be due to sexual selection. For example, men who are hairy may prefer men with more hair than women. It is easier to assess the health of a potential partner if the skin is visible. Skin disease, rashes and other signs that indicate poor health are indicators of a partner who is less likely to be able to reproduce. Visibly smooth and even skin makes a partner more attractive, which in turn leads to less hair. This would be counterbalanced with testosterone, which promotes body hair growth and other characteristics that increase the chances of reproduction. Men ended up being hairier than women. Llorona
When I was younger, I was taught that body hair, particularly pubic hair was meant to be a launchpad for pheromones. Perhaps pheromones have a greater importance for men than for women. Simother
I believe it is easier to bond when a child can touch the mother's skin and not have an insulating fur between them. People who are hairless appear younger and women younger than them are more fertile. Henna Kahra, Uppsala
The question is asked from the viewpoint of the male, which is often considered sexist. Elaine Sporko
The Homo sapiens sapiens interbreeding process with H sapiens, neanderthalis is what gave rise to the body hair genes. High levels of genetic introgression are common in modern human genes that make keratin (a protein component of skin, hair and nails) which is reinforced by backcrossing. The POUF23L variant was introgressed by neanderthals in the genes of 66% of East Asians. In contrast, 70% of Europeans have an introgressed BNC2 allele. The risk of several diseases such as lupus and biliary dysfunction, Crohns disease and type 2 diabetes are all affected by Neanderthal variants. The areas that are most likely to have had both types of humans co-habited have been identified by Palaeontologists for many years. They include the Middle East and southern Europe, as well as the Indian subcontinent. These are also the areas where male body hair is more common as a secondary sexual characteristic. Hippaferalkus
If there was no evolutionary advantage, a trait that uses resources, such as growing a beard, or manes or hairs in other animals, would be considered a disadvantage. If there were a net imbalance of disadvantages in expression, evolutionary pressure would be to alter the visible response to hormones. Sexual dimorphism is common in many species. The most striking differences in sexual dimorphism are those that prove fitness to survive and possibly breed, despite the obvious disadvantage of being visible to predators or devoting energy or features that have no obvious purpose, such as plumes or tail streamers, or displays in many birds. Selection for extreme cases of dimorphism involves being preferred by mates and passing on those genes. Leadballoon
At least in some parts of east London, a beard that is particularly long and full-grown can be a sign that the owner makes great coffee or has access to craft beer. These are strong indicators of a modern homo sapien. HaveYouFedTheFish
Although I am far from being an expert, I did read something once about sexual preferences in birds. It talked about the preferred tail length for females. However, I don't see why it shouldn't be applicable to human hairiness.
It was clear that certain birds preferred shorter tails to longer ones. A longer tail means that a female bird will choose a mate who has a longer length tail. This increases the chance that her children will have a longer tail as well as inheriting that preference. This means that 55% of birds will prefer longer tails, and their offspring will eventually have shorter tails.
If the tail is too long, it doesn't make sense. They would then be less likely survive to reproduce. It doesn't matter if there is an evolutionary advantage or disadvantage. Preferences are to some extent hereditary. These birds are at an evolutionary point in which their tails can be as long as possible before they lose the ability to fly.
Logically speaking, it would only take a few more women who prefer hairy men to hairy women, and that would eventually lead to a preference for the majority. It is important to remember that sexual selection does not always have to be related to evolution. It can be as simple inherited preferences from parents that are passed on to their offspring. Barattin
Because of the wind resistance, less body hair helps to balance naked in wind tunnels. This is something that everyone knows. zblargx
Breastfeeding may be cut shorter by women who have beards that are easy to pull at by their babies. Rosiecyp
I want to know what evolutionary benefit comes from the acceleration of hair growth in my nose and ears in my 50s after going bald 15 years ago! DewinDwl
Less hair means fewer parasites/fleas/ticks, lower risk of vector-related bacterial, viral or parasitic disease, which is probably an advantage for a nursing mother and her child in a cave.
A hunter-gatherer will have more hair and insulation. This is a plus. It seems that men used to spend more time in caves looking for food at the time. A male species is more confident than a female. This could indicate a higher level of testosterone, strength, and dominance.
One thing I don't understand is whether shortsightedness (not being able see clearly from a distance) has any evolutionary advantages. One explanation is that shortsighted males couldn't hunt out and had to stay in cave to help out with domestic problems. They also had more chances to reproduce and so were more likely to pass on their genes to the other members of the group than the alpha male who was out hunting. Petros Aristodemou
Because it stores extra energy, women have thicker layers of adipose tissue. Men lose more heat because their adipose tissue is thinner. This is partially compensated for by the extra body hair. Alan Martin
While most traits don't offer an advantage, they can be used to your advantage. Relative hairlessness in humans may be a result of, for example, walking upright. Or a bigger brain. Regardless of how big we get, this hasn't affected our ability reproduce and adapt to any climate anywhere on the planet. It continues to exist. Pseudaletia
Ask yourself why men have more hair than the women. Hair is not an evolutionary advantage in and of itself. It also has no evolutionary cost. It probably correlates with adaptive testosterone levels, perhaps. It is possible that it has correlated with adaptive testosterone levels. Over the millennia, female choice has resulted in greater male hair. It may also correlate with something that gives men an advantage, such as testosterone. Blackcappedchickadee
Elaine Morgan proposed a time in evolutionary history when people hunted and collected a lot in and around the water. She suggested that there might have been a gender gap in hunting and gathering, with more water-based activities being done by women. This results in a thicker layer over the body and less hair (for streamlining). I am not qualified to comment on the details, but it seems that her theory has some solid foundation. BrianO_Blivion
Elaine Morgan adds that elephants, seals and walruses have similar body hair patterns to those of Elaine Morgan. These mammals are considered to have evolved in the ocean or near the shore. These aqua mammals have body hair that grows in line with the water's flow when they swim. The extra fat in the human breasts is not due to sexual attraction (which is a western oddity), but rather to make them more easily seized by infants when they are wet and slippery. All aqua mammals have midwives present at births. Elaine Morgan is truly brilliant. ShanMorgain
Many of Morgan's arguments and hypotheses have been criticized by evolutionary biologists. Experts have largely dismissed her work as superficially appealing. littlepump
The skin biome is the number of bacteria, viruses, and fungi living on our skin. Body hair allows us to manage it. It is more than a visible sexual signal, which most of the comments address. An examination of male doctors revealed that men who shaved their heads daily caused more infections than their bearded counterparts. Dirkum
These comments make me think that there is a common misconception about evolution. It is linear and agenda-driven. We are always striving for the perfect solution. Evolution is not perfect genetic reproduction mutation. Environment determines whether these mutations are advantageous. It is possible that there were earlier versions of a species that are now dominant.
It would be surprising if female hair is driven by hormones. There are more haired men than women. There are some races with more hair than others. We make micro choices based on what is available. This is our culture. We can pass it on if our cultural preferences don't endanger our well-being. theoliverwall
