Why Haven’t Men Evolved Past Nipples?

The human body has long been a subject of curiosity, but you may be surprised to learn that in terms of evolution, mice could actually be more highly evolved than men in one certain regard – nipples. Whereas men develop a pair of nipples that serve no purpose other than offering slight interest on the chest area, male mice don’t have these markings. In fact, among stallions and male platypuses, mice are among a small cluster of mammalian species that don’t leave the womb with nipples. During early pregnancy, both male and female mice embryos form mammary tissue, which is the foundational tissue that becomes fully-fledged nipples.

In 1999, Yale researchers identified the protein which is responsible for removing the nipples in male mice. In male mice, PTHrP signals the mammary cells to form male hormone receptors, which destroy the tittie and leave male rodents nipple-free. Male humans, however, undergo a similar embryonic process but without the mammary tissue breakdown. After three to four weeks, all embryos develop parallel mammary ridges known as milk lines before 23rd chromosomes, XX or XY, adapt the sexual dimorphisms. As the foetus grows, these milk lines extend to the top of the chest and the lower abdomen recede and just leave a pair of nipples behind, along with the milk-producing glands known as lobules, ducts and the fatty tissue in between. Without a protein such as PTHrP stepping into action to trigger the hormonal roadblocks like it does within certain rodents and mammals, human embryos are built the same way in the breast region.

 

The best explanation for men having nipples is that all embryos, irrespective of gender, start out with them and evolution hasn’t gone far enough yet to remove them off our male counterparts. Because nipples and healthy breast development are so closely linked with female success in the reproductive department, it’s believed by evolutionary biologists that the adaptive pressure to wean out male nipples simply wasn’t strong enough. Because male nipples don’t really have a purpose beyond the decorative, to put them in the same category as the appendix, wisdom teeth and other useless anatomy would be a technical mistake.

 

After all, men’s nipples can’t be relegated to the evolutionary rubbish bin if they can produce milk, which they can! While it may seem absurd, it’s not as far-fetched as it may seem – the hormone prolactin, which facilitates breast milk production, can pass through the placenta into an infant’s body, and after birth that in utero prolactin can cause a newborn to spontaneously lactate regardless of whether it’s a boy or a girl, as both genders have the same breast anatomy during the foetal development stage. This phenomenon is known as witch’s milk and often stops after a few weeks. Evolutionary biologists have long wondered why nipples have remained on the male body for so long given they minimal purpose. Some consider them to be a leftover and, as such, one of the useless parts of the body. The future, highly evolved man could be nipple-free, along with wisdom teeth and the appendix being thrown in the body part bin. After all, in terms of evolution, we’re still only babies – the human race has a long way to go, having only been on the planet a short while in comparison to some other species. Only time will tell if the men of future generations develop in this way.

Categories: evolution, evolutionary biologists, highly evolved, male mice, male nipples, mammary tissue, men, milk lines, nipple free, Nipples, wisdom teeth

The Female Orgasm & its Importance to Human Race

The question regarding female orgasms and their necessity in the process of evolution is one which has been asked many times. And for many people, the concept of questioning it seemed mildly unnecessary in itself – they’re worthwhile to women so who cares about their necessity for the human race? But the topic is a tough one to explore from an evolutionary standpoint. Many biologists do suggest that male non-human primates experience something similar to intercourse, usually judging from a marked change in their body language during ejaculation. So the rationale behind the male orgasm is obvious. For men, orgasm and ejaculation go hand in hand, and with such pleasure preceding the ejaculation, a man is effectively encouraged to spread his seed. A man who experiences orgasm through ejaculation is far more likely to put extra effort into finding sexual partners, than men who ejaculate without any accompanying pleasure. But the physical process of the female orgasm is altogether different. In women, the orgasm isn’t connected to the release of an egg into the uterus, and women can only get pregnant once in any given period of time, so the number of partners is less of an issue in terms of the evolution of a species and its survival.

So why is the orgasm a part of the female sexual experience? It may well be a part of evolutionary adaptation, or it may just be a lucky break. But if it’s down to evolution, what is it offering in terms of survival of a species? Men and women experience very similar physiological changes during orgasm, which usually lasts around a minute. In both sexes, the rectum contracts at intervals of around 0.8 seconds, where lots of muscles in other areas of the body also spasm. There are a number of chemicals which are released at this time, from serotonin to oxytocin. In women, the muscles in the vagina and uterus contract too. These contractions are the basis for one of the evolutionary explanations of the female orgasm – known as the sperm retention theory. Many researchers hypothesise that when the vagina contracts, it is aiming to retain more sperm, to increase the likelihood of getting pregnant. Another theory in keeping with this idea is that orgasm tires a woman out, causing her to lie on her back after sex – it is during this time, researchers say, that more sperm can stay within the body and make its way towards the egg.

 

Currently, the big theory is that women have orgasms for no reason at all – there is no adaptation, it’s simply a wonderful accident which stems from the initial phase of foetal development. This was a popular theory in the ‘70s and has recently seen a revival. In the initial development hypothesis, women simply have orgasms because men do. In the early stages of development within the uterus, the foetus isn’t gendered, and the hormones which determine the gender haven’t yet kicked in. So when the gender is decided, it still has the nerve pathways that create the orgasm. But if this theory is correct, what does that mean for the state of the orgasm in women? If it’s not vital for survival of the species, will it be phased out? What we can determine is that there is still a long way to go before we know the real reason for the female orgasm – its cryptic purpose still baffles researchers to this day.

Categories: Ejaculation, evolution, female, female orgasm, orgasm, Sex, theory, Women

What Will the Human Face Look Like in 100,000 Years?

You can’t tell a lot about the distant future, but educated guesses can take you a long way. This was the thinking behind a project undertaken by artist and researcher Nickolay Lamm with help from Dr. Alan Kwan, who has a doctorate in computational genomics from Washington University. These wellness experts set out to answer the question: What do you think the human face might look like in 100,000 years and why?

 

Lamm and Kwan took the reasoning that, with our advanced genetic engineering technology, this may make more of an impact on human wellbeing over time, and take over the role that has so far been played by natural selection. From this reasoning, Lamm created a series of images that he believes will resemble something of the average human in 20,000 years, 60,000 years and 100,000 years time. Although the man and women used for the project are both Caucasian, Lamm was quick to point out that you shouldn’t read too much into that, as the decision to use these models simply came down to the fact that they were the best he could find.

 

20,000 years: From an image of a man and woman today, Lamm moves onto one that takes place in 20,000 years time. Although the couple is the same, their faces show a few minor changes. To accommodate larger brains, their heads are a little bit bigger. Lamm has also included yellow lenses on the models to indicate special lenses that act kind of like Google Glass does today, but in a much more powerful way.

 

60,000 years: Jumping forward another 40,000 years, the 60,000-year image shows the beginning of major changes. Not only are the heads even larger than the previous image, but the eyes have also grown. According to Lamm, this is based on the idea that humans have colonised the solar system in 60,000 years time, and are now living further away from the sun. This means that there’s less light, and so your skin pigmentation would change, but also your eyelids would become thicker as you’re outside the Earth’s protective ozone layer, and would need more protection against UV rays.

 

100,000 years: It’s at this point in our future that Lamm predicts big changes. The most shocking thing is that he predicts big Japanese Manga-style eyes that may feature ‘eye-shine enhance low-light vision and even a sideways blink from re-constituted plica semilunaris,’ offering extra protection against cosmic rays. Lamm believes the future human will follow the “golden ratio proportions” of a perfectly symmetrical face from left to right, as well as having larger nostrils to enhance off-planet environmental wellness. Denser hair is also predicted in the future, as this can help to contain heat loss from their even larger heads.

 

Michael Graham Richard, editor of TreeHugger’s Science & Technology and the Cars & Transportation categories, comments, ‘I would say that the timeline is probably too long. We’re already starting to have the ability to modify ourselves, so if we ever decide to do so (it’s probably a question of “when” rather than “if”), it probably won’t take thousands of years. Just in the past 100 years, we’ve gone from barely having mastered powered flight with the Wright Brothers to landing space probes on almost all planets and moons of the solar system, from Morse code telegraphs to a worldwide communication network made up of billions of electronic devices, each of which is more powerful than the supercomputers of a few decades ago…The human race’s capabilities in 50 years should be even more impressive to us today than today’s tech would be for someone from 50 years ago — and that’s saying something.’

Categories: Design Project, evolution, human, Human Face, lamm, nbsp, today, years, years time

R-evolutionary Study: Did Men Cause Menopause?

The next time your wellness is affected by the hot flushes, night sweats and mood swings of menopause, blame the nearest male. According to evolutionary geneticists from Canada’s McMaster University, who published their findings in PLOS Computational Biology, men’s tendency to choose younger mates meant fertility became pointless for older women over the years, which eventually led to the menopause.

Human beings are the only species in which females cannot reproduce throughout their lives, and this has long puzzled researchers. It has been surmised that women lose their fertility at an age where they might not live to see a child grow, and instead are available to care for younger women’s children. This is known as “the grandmother effect” and put menopause in the light of a block to older women from continuing to reproduce. Yet this new study suggests just the opposite; the lack of reproduction has given rise to menopause.

Study leader Professor Rama Singh, an evolutionary geneticist, commented that men choosing younger mates were “stacking the odds” against continued fertility. ‘There is evidence in human history; there was always a preference for younger women,’ he said, adding that they were looking at human development many thousands of years ago – rather than current social patterns. ‘The social system is changing. There are women who are starting families later, because of education or a career.’ Professor Singh noted that this, plus later childbirth, could potentially alter the timing of the menopause, over a significant period of time. Women may have later menopause, and those genes could be passed on to their daughters ‘with the possibility of menopausal age being delayed.’

However this theory has been challenged by Dr Maxwell Burton-Chellew, an evolutionary biologist in the department of zoology at the University of Oxford. According to Dr Burton-Chellew, ‘The authors argue that the menopause exists in humans because males have a strong preference for younger females. However, this is probably the wrong way round – the human male preference for younger females is likely to be because older females are less fertile.’

‘I think it makes more sense to see the human male preference for younger females largely as an evolved response to the menopause, and to assume that ancestral males would have been wise to mate with any females that could produce offspring,’ Dr Burton-Chellew explained. ‘Evolutionarily-speaking, older females faced an interesting “choice”: have a child that may not reach adulthood before your own death, or stop reproducing and instead focus on helping your younger relatives reproduce.’

Categories: evolution, Menopause, Research

Are We Sexually-Attracted to Voices?

When we are looking for a partner, whether for sexual or emotional attachment, we look for the many ways in which they can be appealing to us. Sometimes, it’s those cheeky locks of hair over a woman’s shoulders. Sometimes it’s the intensity in a man’s gaze. Others, it could be a matter of body shape; but what if we took into account how a person sounds as well?

It is no secret that women prefer men with deep voices, whilst men prefer women with high, youthful tones, but a paper published by PLOS ONE has taken it one step further.

According to a research group led by Yi Xu, the preference is due to body size.

Amongst a group of 32 participants, female voices with a high pitch were thought to have smaller body sizes, which in turn, was deemed attractive by male listeners.

Contrary to that, the sounds of a deep, throaty male voice suggested that the man had a large frame, considered more attractive when the voice had a certain “breathiness” to it, suggesting a reduced amount of aggression.

The research was done by manipulating computer-generated voices. Participants were asked to listen to a variety of phrases spoken. Each time, the voice pitch, rise-and-low frequencies and other traits were edited so that participants could pick a preference.

The men preferred the high-pitch, which suggested a smaller female – to a point. Any higher and the voice was deemed unattractive.

Similarly, female participants were given the same test, but this time, the male voice was given the trait of supposed “breathiness”, which apparently took the edge off a male voice. It kept the suggested nature of a man with a large frame, but took away the aggression that seemed to be in-tow. Additionally, male voices with “breathiness” sounded happier.

Whether or not the findings are substantial, it all points towards the idea of ideal figures to pass along one’s genes. The primal instinct to reproduce is an intriguing one, as is the capacity to attract the sexes.

Of course, life is getting more complicated, with primal urges taking a back seat to let emotions, enjoyment and dating swing into high tide.

Rather fun, in hindsight.

Are We Sexually-Attracted to Voices?

Categories: Attractiveness, evolution, genetics, sexual health, Voices