Happy Valentine’s day! Testicle size and mating systems

I really despise Valentine’s day because I do not appreciate society telling me when I should feel romantic and loved-up and when I should not. HOWEVER as a bit of fun, I thought I would write a post about love, romance and sex but most importantly SCIENCE!

And testes*.

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Testicles are funny things, and almost all healthy male vertebrates boast two of them. In many mammals, including ourselves, they hang from the body in a scrotum because the valuable sperm they contain are mighty fussy, and mammalian body temperature tends to be just a little too hot for them. So natural selection kindly began dangling the sperm of males from two sacs between the rear legs, nice work evolution. But it turns out that we can tell a lot about a species’ mating system (i.e. how monogamous or promiscuous they are) just from looking at the size of the male testis. The diagram below is both hilarious and helpful:

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Here you can see the gonad size of various primate species in relation to body size. The top row are the males – the big circle represents their body size, the arrow is the penis and the balls are, well, the balls. (No laughing at the gorilla and yes guys, your penis is quite large compared to our primate cousins). The bottom row shows the female sexual organs of the same species – I can’t help but giggle at the human female. MASSIVE BOOBIES!

So the size of the testes can tell us a lot of information about the mating system adopted by various species. We have to remember that although in our culture monogamy is often (rightly or wrongly) seen as the norm, this is far from the case in most other mammalian species. There are lots of different mating systems: monogamy (one male one female), polygyny (one male, several females), polyandry (one female, several males) and promiscuity (basically a free-for-all orgy where it is completely acceptable for anyone to have sex with anyone).

Males of species with promiscuous mating systems (such as chimpanzees) tend to have the largest testes, and this makes sense because of something called sperm competition. In a promiscuous mating system, lots of males are having sex with lots of females, and everyone wants a good shot at fathering the most offspring, because this means passing on your genetic material and is a big fat evolutionary WIN. So for this reason it is advantageous to have a lot of sperm, and big old testes to store the little guys in.

However, the males of species with polygynous mating systems (e.g. gorillas)  tend to have smaller testes, because a single male has almost guaranteed access to at least a couple of females. So there is no need to waste extra energy on producing lots and lots of sperm in giant testicles, because his chances of impregnating a female is pretty high and he has no competition to wane off.

Now I know what you’re thinking. Where do we fit in all of this? Well guys, I have to say, your testicles are classified as “moderate”. Bigger than a gorilla, but shy of a chimp. This actually fits well into the mating system hypothesis – although humans are often socially monogamous, they do participate in moderate levels of non-monogamy (SHOCK HORROR KLAXON)!!

So there you have it. The bigger the balls, the more promiscuous the sexy-times. But smaller testicles aren’t for losers – it just means they don’t have to try so hard! Quality over quantity perhaps? Maybe that just means more time and energy can be spend on post-coital cuddles or, you know, child-rearing.

So whether you have testes or ovaries, and regardless of their size, I wish you all a very happy and sexy V-day.

A bonobo with large testicles chillin’ out.  Source

*I will leave it up to you to guess what type of mating system this squirrel may participate in.

Science saved smooching from the anti-kissing league

At the start of the 20th Century, the people of the western world were becoming increasingly aware of what infectious diseases were and how they were spread. The public were understandably anxious about catching such an illness; among the top causes of death in 1900 were infections like influenza and tuberculosis. This anxiety led to some taking rather extreme measures to lower the risk of infection – including anti-kissing leagues.

Taken from a newspaper article from August 28th, 1905

If you can’t quite make out what the article says, it beautifully states that “members of the league take a solemn pledge not to kiss each other, in public or in private, their contention being that kissing is the means of conveying contagious diseases from one fair lip to another”. The Anti-Kissing Leagues of Paris and Vienna were totally against kissing in general and were seen as the most hardcore of all the anti-kissers, claiming “indiscriminate kissing is more dangerous than a motor smash”.

22nd November 1927

The French claimed that 40,000 germs were transferred in every kiss and so the solution seemed simple – tell people about this disgusting fact, and humanity shall smooch no more and we can wave goodbye to infectious disease. Believing that they had cottoned onto an idea stolen from the Japanese – all kissing scenes had to be cut from European and American films before they were shown in Japan – the French supposed that the reasoning behind this was because the Japanese did not wish to get ill and so would not promote such a vulgar practice as kissing.

But the Americans were having none of this anti-kissing nonsense, it would seem: They called on SCIENCE, and in 1927 a neat little experiment was published in the popular science magazine Science and Invention. Participants were invited to kiss a Petri dish containing a sterile culture medium. After their romantic encounter, the Petri dishes were incubated for 24 hours, allowing any germs that had been transferred from grotty human lips to the sterile culture to multiply into little visible colonies of bacteria. The scientists counted these bacteria, and concluded that far from the French estimate of 40,000, a mere 500 germs were transferred in a kiss – although women wearing lipstick passed on ~200 more.

So kissing does involve the transfer of bacteria, but not as much as we once thought. And if you really worry about these things, avoid kissing people who are wearing lipstick. But I think we should all say a big THANK YOU to science for allowing us to shneck, smooch and snog as much as we like.

I read about this experiment in The Mad Science Book by Reto U. Schneider which is awesome, you should check it out.

On animal research

As I was wandering aimlessly around Newcastle town centre today, I heard a couple of older women talking. The only snippet of conversation I made out was something along the lines of “it’s terrible all this research they do on animals these days”. This really made me think, because as a (I hope) scientifically literate individual, my initial reaction was “pfffft clearly they don’t know a thing about animal research”. Then I paused for a second and remembered that as a teenager (not that many years ago), I was against animal research. (It is worth noting here that as a teenager I also wanted to become a member of Greenpeace and attended all the anti-war protests I could; all at a time of my life where I genuinely thought it was “cool” to go to Edinburgh for the day dressed in my pyjamas armed with vodka in a Tango bottle and 10 Lambert & Butler). Anyway, I digress. The point I’m making here is that all too often we assume that “most people” are like us, and have similar views and attitudes to us. But they don’t. And with a topic as controversial as animal research, I can completely understand why people have such strong and opposing views. So for what it’s worth, and as someone who has gone from one extreme view to another, here is my primer on animal research.

Why are people anti-animal research?

I believe the main reason that so many people are violently against animal research is due to a highly emotive subject paired with a lack of knowledge and education: This certainly was the case with my 15-year-old hippie-wannabe self. It seemed obvious to me that you could not simultaneously be an “animal lover” and pro-animal research. But I now realise that is utter nonsense. But that’s not what animal rights extremist groups would have you believe. They like to bombard the public with pictures like this:

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Yes, this is a horrible image. But it is also a very old image and if you look hard enough I’m sure you’ll find other horrifying images of human behaviour from this era, like torturing fellow humans because of their religion or sexual orientation. My point is that you cannot judge current issues on what you think you know about the past. We learn from our mistakes, science advances, we move on. Don’t let stock shock and very often manipulated images like this make your mind up for you.

The truth about animal research

Have you ever been prescribed antibiotics? Are you up to date with your vaccinations? Do you know anyone who receives medicine for athsma, diabetes or high blood pressure? Guess what – we received these treatments thanks to years of research on animals. The fact is that without animal research, we would not have the life-saving medicines we have today. Therefore when people say “there is no clear benefit to humans from using animals in research”, you can tell them that they are wrong.

Despite what horror stories you may have heard or shocking stock animal rights images you may have seen, animal research is and must be carefully regulated. Three separate licences are required in order for any animal research to be carried out: a personal licence for the researcher, a project licence for the study, and a licence for the place where the research is done. In reality, due to extremely high standards and regulations, most lab animals are likely to enjoy a higher standard of welfare and care than your average household pet. According to a publication by the organisation Understanding Animal Research:

“Government vets and doctors make regular, and often unannounced, visits to make sure that the animals are being properly looked after. On their recommendation, licences can be removed and facilities closed down if rules are broken. Almost without exception, animals are specially bred for research and testing. Many studies cause little suffering. Typically, trained researchers give doses of a potential medicine, take small blood samples or scan the animal to check painlessly inside its body. Technologists and vets are on hand to look for the smallest signs of pain or distress.”

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The three Rs

The three Rs refers to three techniques that are required by law to be used instead of animal research, unless it is completely necessary. These are replacement, refinement and reduction.

Replacement  techniques are those which result in the replacement of animals in research with other models, such as computer models. I often hear people saying “why do we still need animal research when we have computer models? In truth, although advances in science and technology mean that animals are now used in fewer situations, some animal research is still essential for medical progress.

Refinement refers to the welfare of any animals being used in research. This is important not only from the perspective of our moral duty to minimise any pain or suffering to an individual animal, but also for the research itself: Animals who are not distressed and live longer lives lead to much more reliable and worthwhile data.

Reduction means using as few individual animals as possible in a given study. This can be achieved by good experimental design and statistical analysis.

So remember that by law, scientists are only allowed to carry out research on animals if all of the above guidelines have been met. Permission will not be granted if animals are not essential to the research, if their welfare is not of a good standard, and there are checks on how many animals can be used.

Final thoughts

One of the key arguments used by animal rights extremists is that the scientific community is being secretive, because they have something to hide, like animal research is their dirty little secret. This is not true; plenty of scientists who use animal models talk about their work, they publish journals and speak at conferences. The reason they may not do so much public engagement with those outside their field is because of the ever-lurking menace of animal rights extremists. This is a bigger problem in the USA than it is here in the UK, but it is still a very real threat. If your family is being threatened because of the work you do in the lab, would you want to talk openly and publicly about it? Thankfully, public support for animal research is increasing, and this is a Good Thing for everyone. If scientists were able to do their work without fear of backlash from animal rights groups, we would ultimately see  an improvement both in the welfare of the research animals (for example, some UK universities have animals which would benefit from outdoor enclosures but their visibility as lab animals would make them a vulnerable target) and in the scientific progress being made.

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