Guest Post: Why did humans evolve big penises but small testicles?

by Mark Maslin, UCL

Humans have a much longer and wider penis than the other great apes. Even the largest of gorillas, more than twice as heavy as a human, will have a penis just two and half inches long when erect.

However our testicles are rather small. A chimpanzee’s testes weigh more than a third of its brain while ours weigh in at less than 3%. The relative size of our penis and testes is all down to our mating strategies, and can provide some surprising insights into early human culture.

Primates exhibit all sorts of mating behaviour, including monogamous, polygynous – where males have multiple mates – and multimale-multifemale. One indicator of which behaviour occurs in a species is the size difference between males and females. The greater this sexual dimorphism, the more likely the mating is either polygynous or multi-male to multi-female. This can be shown by observing chimpanzees and gorillas, our closest living relatives.

Male chimpanzees are much larger than females, and they have a multi-male to multi-female mating system. Essentially, male chimps have sex all the time with any female and with any excuse. A female therefore may contain sperm from multiple partners at any one time, which puts the sperm itself – and not just the animals that produce it – into direct competition. For this reason, chimpanzees have evolved huge testicles in order to produce massive amounts of sperm, multiple times a day.

Male gorilla are also much larger than females, but they have a polygynous or harem-style mating system where many females live with a single male. With little or no competition actually inside the uterus, gorillas have had no need for a testicular arms race to facilitate the production of more and more sperm. Their testes, therefore, are relatively small. This is similar to modern humans, whose testes are also of very modest size and produce a relatively small amount of sperm. In fact human sperm count reduces by more than 80% if men ejaculate more than about two times a day.

Chimps have huge testicles for their size.
Steffen Foerster / shutterstock

The human penis is large when compared with those of our closest relatives: chimpanzees, gorillas, and orangutans. However, primatologist Alan Dixson in his wonderfully detailed book, Primate Sexuality, suggests that if we look at all primates, including monkeys, this is just wishful thinking.

Comparative measurements show the human penis is not exceptionally long. The Hamadryas baboon, for instance, a native of the Horn of Africa, has an erect penis that is five and half inches long – slightly shorter than an average human male, but they weigh only a third of our weight.

Some of the complex penises found in multi-male to multi-female mating primates such as chimpanzees (h), brown lemurs (a) or macaques (d, e, f).
Alan F. Dixson, Primate Sexuality

The human penis is in fact extremely dull – it does not have lumps, ridges, flanges, kinks or any other exciting feature that other primates have. In primates, this lack of penis complexity is usually found in monogamous species.

Monogamy mystery

This observation clashes with the fact that men are significantly larger than women. This suggests our evolutionary background involved a significant degree of polygynous, rather than exclusively monogamous, mating. This is supported by anthropological data showing that most modern human populations engage in polygynous marriage. Anthropologists Clellan Ford and Frank Beach in their book Patterns of Sexual Behaviour suggested that 84% of the 185 human cultures they had data on engaged in polygyny.

Primates with simpler penises tend to be monogamous like cotton top tamarins (a) or polygynous like gorillas (g).
Alan F. Dixson, Primate Sexuality

However, even in these societies most people remain monogamous. Polygynous marriages are usually a privilege reserved only for high status or wealthy men. It is worth noting that hunter-gathers around the world practice only monogamy or serial-monogamy which suggests that our ancestors may have used this mating system.

At first sight, however, it would seem sensible for males to reproduce with as many females as possible. Human monogamy has long puzzled anthropologists, and lots of effort has gone in to working out what keeps males hanging around.

Three main theories have been put forward. First is the need for long-term parental care and teaching, as our children take a long time to mature. Second, males need to guard their female from other males. Third, our children are vulnerable for a long time and infanticide could be a risk from other males. So to ensure that children are able to reach maturity the male is likely to stay to protect them, both socially and physically. This may be why males have maintained their larger relative size.

Hamadryas baboons have unusually long penises.
المُصوّر: مُعتز توفيق إغباريّة, CC BY-SA

If we view the evolution of monogamy mating systems in humans through the lens of human society it is clear that it takes a huge amount of social effort to maintain and protect more than one mate at a time. It is only when males have access to additional resources and power that they can protect multiple females, usually by ensuring other males protect them. So monogamy seems to be an adaptation to protect one’s mate and children from other males. This monogamy is reinforced by the high social cost and stress of attempting to do this for multiple partners, and it has become supported by cultural norms.

So when living in complex human societies the largest and most important sexual organ is the brain. Somewhere in our evolutionary past how smart and social we are became the major control on our access to sexual partners – not how big or fancy a male’s penis is.



Mark Maslin, Professor of Palaeoclimatology, UCL

This article was originally published on The Conversation. Read the original article.

From the Archives: Belafonte criticizes Barack Obama on civil liberties in Charlottesville

Publisher's note: This article was originally published on Examiner.com on January 24, 2012. The Examiner.com publishing platform was discontinued July 1, 2016, and its web site went dark on or about July 10, 2016. I am republishing this piece in an effort to preserve it and all my other contributions to Examiner.com since April 6, 2010. It is reposted here without most of the internal links that were in the original.

Belafonte criticizes Barack Obama on civil liberties in Charlottesville

Harry Belafonte in Charlottesville - January 2012

Harry Belafonte – actor, author, singer, and political activist – appeared in Charlottesville on January 24 at a screening of his autobiographical film, Sing Your Song, as part of a community celebration of the life of Martin Luther King, Jr., who was a close friend and colleague of Belafonte’s in the civil rights movement of the early 1960s.

In a discussion led by University of Virginia history professor Julian Bond at the historic Paramount Theatre, Belafonte reflected on his life and career, offered his thoughts on politics, culture, education, and other topics, and criticized President Barack Obama’s record on protecting civil liberties.

‘Critical of the president’

Replying to a question posed by a member of the audience, Belafonte prefaced his remarks by promising that he would vote for Barack Obama’s re-election and would campaign for him this year.

“But recent utterings,” he cautioned with a smile, “have unsharpened my dance card to come to the White House for the next ball.”

Turning more serious, he added, “I’ve been critical of the president and I’ve let that go public.”

Referring to the Universal Declaration of Human Rights, which had been drafted by his friend, Eleanor Roosevelt, in the 1940s, Belafonte pointed out that the human rights record of any country “becomes the first litmus test of how we create policy in relationship to the country under examination.”

That litmus test, he suggested, has to be applied to the United States as well as any other country.

‘Patriotic treason’

Paraphrasing Theodore Roosevelt, Belafonte argued that “if a citizen finds himself at the crossroads of a moment when the people, who have been invested with the power to lead this nation, begin to betray the Constitution of this country and betray the citizens of this country, it is not only the right but the responsibility of any citizen and all citizens to raise their voice against this evil, and anyone who does not do that should be charged with patriotic treason.”

In that context, he said, Barack Obama had “laid out his mission, not with complete clarity” but with enough substance “for us to linger with hope.” Obama had promised, upon taking office, that he would end the wars – yet they continue.

In addition to the wars in Iraq and Afghanistan, Belafonte identified something else of concern.

“More important,” he said, are “the homeland security laws, which were written to such extremes that they defied imagination that anyone could have thought of those laws.”

That those laws made their way through Congress and were signed by the President, he said, “was an absolutely stunning experience for all of us, and certainly for some of us who saw it in the depth of its villainy.”

Looking out over the audience, Belafonte painted a darkly dramatic picture of the effect of laws like the USA PATRIOT Act and the recently passed National Defense Authorization Act (NDAA), signed on December 31 by President Obama.

“Anyone who is sitting in this room tonight,” he said, “could walk out of that door and be whisked away by strangers, people who you’ve never met [and] don’t know, whose task it was to apprehend you and never tell you why you’re being apprehended, never tell you what you’re being charged with, never ever give you the right to make a phone call or get the benefit of a lawyer.”

‘Deeply wrong’

If someone is willing to surrender his rights, he said, or “willing to surrender all that is precious” under the framework of the Constitution, then “something’s wrong. Something is deeply wrong.”

Belafonte then explained the importance of the system of checks and balances found in the American constitutional system.

“The House watches the Senate, the Senate watches the House, both watch the Executive, the Executive watches the House and the Senate,” and the Supreme Court is “the final arbiter” for what becomes “the law of the land.”

When that system is out of balance, however, it needs “a leader who is made of such moral courage and strength to step into this frame and put himself on the line.”

By his tone of voice, Belafonte implied that Barack Obama lacks that courage and that strength.

“It is said by some,” the activist pointed out ruefully, “that Barack Obama’s second term as President will reveal all these mysteries [and] will reveal all these good deeds. He just needs to get the second term.”

Unfortunately, Belafonte added, “I’m not quite that optimistic. I’m not too sure that what we saw in the first term will not be” much different from “what we see in the second term.”

Even with that note of pessimism, he concluded, he is “infinitely more prone to devote all of my resources into his camp” than he would be willing to support any of the potential Republican candidates seeking to unseat Obama.

With that, Belafonte left the stage so he could autograph copies of his new book, My Song: A Memoir, for several dozen local fans.

The Big Lie and How It Travels

After White House Press Secretary Sean Spicer audaciously lied, in his first news media briefing, about the attendance estimates at Friday's presidential inauguration, a friend on Facebook posted an analysis that has since gone viral on social media, particularly on Twitter.  For instance, Oscar-winning composer John Legend, Helen Hayes award-winning actor Will Gartshore, and Republican political consultant Ana Navarro all tweeted a screenshot of the mini-essay to their thousands of Twitter followers.

The provocative analysis has caused a stir -- a real conversation about facts, lies, and propaganda -- so, since the original author gave his permission to "copy and paste" his status as long as his name was removed and the originator remained anonymous, I'm offering it here to expand its reach. It deserves to be read, reposted, restated, and challenged.

The White House

If you are puzzled by the bizarre "press conference" put on by the White House press secretary this evening (angrily claiming that Trump's inauguration had the largest audience in history, accusing them of faking photos and lying about attendance), let me help explain it. This spectacle served three purposes:

1. Establishing a norm with the press: they will be told things that are obviously wrong and they will have no opportunity to ask questions. That way, they will be grateful if they get anything more at any press conference. This is the PR equivalent of "negging," the odious pick-up practice of a particular kind of horrible man (e.g., Donald Trump).

2. Increasing the separation between Trump's base (1/3 of the population) from everybody else (the remaining 2/3). By being told something that is obviously wrong—that there is no evidence for and all evidence against, that anybody with eyes can see is wrong—they are forced to pick whether they are going to believe Trump or their lying eyes. The gamble here—likely to pay off—is that they will believe Trump. This means that they will regard media outlets that report the truth as "fake news" (because otherwise they'd be forced to confront their cognitive dissonance.)

U.S. Capitol

3. Creating a sense of uncertainty about whether facts are knowable, among a certain chunk of the population (which is a taking a page from the Kremlin, for whom this is their preferred disinformation tactic). A third of the population will say "clearly the White House is lying," a third will say "if Trump says it, it must be true," and the remaining third will say "gosh, I guess this is unknowable." The idea isn't to convince these people of untrue things, it's to fatigue them, so that they will stay out of the political process entirely, regarding the truth as just too difficult to determine.

This is laying important groundwork for the months ahead. If Trump's White House is willing to lie about something as obviously, unquestionably fake as this, just imagine what else they'll lie about. In particular, things that the public cannot possibly verify the truth of. It's gonna get real bad.

The point is, if the Trump administration and the President himself are willing to lie about such petty things as the number of people who were or were not on the National Mall on January 20, what will they do when they want to send American soldiers into battle in some far-off place? What will they do when the Bureau of Labor Statistics issues a monthly unemployment figures that is unflattering to the Administration? What will they do when the number of anti-Administration protesters far outnumbers the guests at the inauguration?

A final note: Doonesbury cartoonist Garry Trudeau proves himself amazingly adept at interpreting Donald Trump. His comic strip today, which had to have been drawn days before the inauguration, as the President in the White House challenging the news media's reports on the inauguration's attendance numbers. You can't make this stuff up.

Update: Russian chess champion and political dissident Garry Kasparov made a similar, and pithy, point on Twitter:

The point of modern propaganda isn't only to misinform or push an agenda. It is to exhaust your critical thinking, to annihilate truth.

— Garry Kasparov (@Kasparov63) December 13, 2016

A Quick Transition: Inauguration 2017

This is what the White House web site landing page looked like at 11:59 a.m. on January 20, 2017:

And this is what it looked like at 12:01 p.m. on January 20, 2017:

Proof positive that Donald J. Trump is the 45th President of the United States.

From the Archives: Justin Bieber, Gary Becker, and the future of marijuana prohibition

Publisher's note: This article was originally published on Examiner.com on January 7, 2013. The Examiner.com publishing platform was discontinued July 1, 2016, and its web site went dark on or about July 10, 2016. I am republishing this piece in an effort to preserve it and all my other contributions to Examiner.com since April 6, 2010. It is reposted here without most of the internal links that were in the original.

Justin Bieber, Gary Becker, and the future of marijuana prohibition

What do teen heartthrob Justin Bieber and a Nobel prize-winning economist have in common?

It turns out that both, in their own way, have made a strong argument in favor of ending the War on Drugs.

Bieber, the Canadian singer and actor, was allegedly caught on film smoking a blunt (marijuana in a cigar wrapper), as reported by celebrity gossip site TMZ. The incident occurred not long after Bieber was involved in a traumatic accident that resulted in the death of a paparazzo trying to photograph the teen idol in his white Ferrari on a Los Angeles street.

Soon after the photographs surfaced, Bieber tweeted to his fans: “everyday growing and learning. trying to be better. u get knocked down, u get up” – not an apology but a subtle acknowledgment that the allegations may have substance.

Losing the war

The same day that TMZ published the Bieber photos, Nobel laureate economist Gary Becker published an article in the Wall Street Journal asking, “Have We Lost the War on Drugs?”

Becker and his co-author, University of Chicago economist Kevin Murphy, point out that the “paradox of the war on drugs is that the harder governments push the fight, the higher drug prices become to compensate for the greater risks. That leads to larger profits for traffickers who avoid being punished. This is why larger drug gangs often benefit from a tougher war on drugs, especially if the war mainly targets small-fry dealers and not the major drug gangs. Moreover, to the extent that a more aggressive war on drugs leads dealers to respond with higher levels of violence and corruption, an increase in enforcement can exacerbate the costs imposed on society.”

Becker and Murphy argue for, at the very least, decriminalizing now-illegal drugs, as Colorado and Washington state voters did with regard to marijuana in last November's election.

“Decriminalization of all drugs by the U.S. would be a major positive step away from the war on drugs,” the economists said in the Wall Street Journal.

“In recent years, states have begun to decriminalize marijuana, one of the least addictive and less damaging drugs. Marijuana is now decriminalized in some form in about 20 states, and it is de facto decriminalized in some others as well. If decriminalization of marijuana proves successful, the next step would be to decriminalize other drugs, perhaps starting with amphetamines. Gradually, this might lead to the full decriminalization of all drugs.”

Saving money, raising revenue

Becker and Murphy are not the first notable economists to argue for an end to the drug war on the grounds that it is economically indefensible.

In 2005, a statement signed by 500 economists, including Nobel laureate Milton Friedman and several from Virginia's George Mason University, argued that ending marijuana prohibition “would save $7.7 billion per year in state and federal expenditures on prohibition enforcement and produce tax revenues of at least $2.4 billion annually if marijuana were taxed like most consumer goods. If, however, marijuana were taxed similarly to alcohol or tobacco, it might generate as much as $6.2 billion annually.”

The absence of a public outcry over Justin Bieber's alleged pot smoking, along with the Colorado and Washington initiatives and the adoption of laws permitting the medicinal use of marijuana in 18 states, suggest that the American people are more open to a rational discussion about ending the drug war. Bieber's non-apology on Twitter itself suggests that he views the incident as uncontroversial and unworthy of further attention.

While Gary Becker and other economists make erudite and logically rigorous arguments against drug prohibition, Bieber's near-silence is eloquent in its own way and equally compelling.

Politicians do not seem to be following expert opinion or public sentiment, however. While two years ago, then-Delegate Harvey Morgan (R-Gloucester) introduced legislation with the effect of decriminalizing marijuana possession, this year the emphasis in the Virginia General Assembly seems to be toward extending the reach of drug laws. Delegate Bill Carrico (R-Grayson County), for instance, has submitted a bill that would require welfare recipients to be tested for cannabis and other drugs. Nobody in Richmond seems to have taken on Delegate Morgan's mantle in the wake of his retirement.

Eventually, as Becker and similar thinkers point out, the law will catch up to public opinion.

Guest Post: What the magi had in common with scientists

by Roger Barlow, University of Huddersfield

Picturesque and exotic, with their crowns and camels, the three kings regularly appear on Christmas cards and in nativity scenes. But how much is original, and how much is later addition for the sake of a good story?

All we know is what Matthew’s gospel tells us, and that does not include their number. They brought gifts of gold, frankincense and myrrh, but to suppose that three gifts means three givers is no more than a guess. More importantly, they were not kings. In his account Matthew consistently describes the visitors as magoi which is the same as the English word “mage”. It’s an unusual word and is often translated as “wise men”.

The early church upgraded them to royal status, perhaps because of descriptions in Isaiah 60 and Psalm 72 of kings worshipping the messiah – but Matthew himself, whose gospel is full of references back to the psalms and prophets, does not make this link, and he would never have let such an opportunity drop.

What they saw

They had seen a star, which shows they were astronomers – or astrologers as there was no difference back then. What was this star? Some scholars have posited that in 7BC there was a triple conjunction (when the planets catch up and overtake each other: quite a dramatic sight) of Jupiter and Saturn, in the constellation of Pisces. These three elements were linked in astrology to royalty, the messiah and the Jews respectively.

Some astronomers, for example Patrick Moore, are unhappy with this theory and suggest that the star the wise men followed was a nova, a comet, or meteors. But there is no firm evidence for any of these. They point out that conjunctions are rare but not unique, and ask why were there no emissaries to Israel on other occasions. Perhaps there were – we only have this single record because of its link to the larger story.

I think what really worries them is that if you accept this interpretation it implies accepting the validity of astrology, and today’s astronomers really hate astrologers (never ask an astronomer what their star sign is). But you don’t have to. Even the sceptical can accept that a visit to Jerusalem and Bethlehem by foreigners looking for the messiah would have made a good story which would be told and retold – and eventually get attached to the birth of Jesus. Matthew wrote his gospel for a Jewish readership, and the Jewish religion then was hostile to astrology, so the suggestion that he just made up the story as propaganda is implausible.

A familiar approach

We can imagine the situation. The star was not a surprise: conjunctions are predictable – today lists of upcoming ones are available on the internet – and even if this was not available 2,000 years ago, astronomers then made careful observations on which they could make predictions using geocentric theories which were fundamentally wrong but which nevertheless seemed to work.

Stonehenge astronomical observatory

For months and years beforehand the “wise men” will have discussed and organised the expedition: the practicalities, the funding. We know how they must have felt, planning a project, looking for money to pay for it, arguing whether their theory’s predictions were really firm or could have some other interpretation.

At this point we realise that we have a better word to translate magoi – a word not available to the translators of the Authorised Version of the Bible in King James’ reign, as it was only invented in 1833.

The word is scientists.

Looking back 2,000 years, they and we are not so different. They used their understanding of the universe to predict what would happen in the world – and, working as a group, they investigated their predictions, despite the cost and trouble and hardships. This is something any scientist today can recognise and identify with. Their understanding of the universe is crude and primitive in our eyes – but what will today’s scientific theories look like in 2,000 years time?

So, when we see pictures of the three kings at Christmas, we should spare them a thought, as colleagues who believed in their theories and followed through the consequences, despite the trouble and expense and personal effort involved. The strength of their conviction and their resolution to follow it, 2,000 years ago, can be an example to us today.



Roger Barlow, Research Professor and Director of the International Institute for Accelerator Applications, University of Huddersfield

This article was originally published on The Conversation. Read the original article.

Guest Post: The psychology of New Year’s resolutions

by Mark Griffiths, Nottingham Trent University

Research has shown that about half of all adults make New Year’s resolutions. However, fewer than 10% manage to keep them for more than a few months.

As a professor of behavioural addiction I know how easy people can fall into bad habits and why on trying to give up those habits it is easy to relapse. Resolutions usually come in the form of lifestyle changes and changing behaviour that has become routine and habitual (even if they are not problematic) can be hard to do.

Happy New Year, 2017!

The most common resolutions are: losing weight, doing more exercise, quitting smoking and saving money.

The main reason that people don’t stick to their resolutions is that they set too many or they’re unrealistic to achieve. They may also be victims of “false hope syndrome”. False hope syndrome is characterised by a person’s unrealistic expectations about the likely speed, amount, ease and consequences of changing their behaviour.

For some people, it takes something radical for them to change their ways. It took a medical diagnosis to make me give up alcohol and caffeine and it took pregnancy for my partner to give up smoking.

To change your day-to-day behaviour you also have to change your thinking. But there are tried and tested ways that can help people stick to their resolutions – here are my personal favourites:

Be realistic. You need to begin by making resolutions that you can keep and that are practical. If you want to reduce your alcohol intake because you tend to drink alcohol every day, don’t immediately go teetotal. Try to cut out alcohol every other day or have a drink once every three days. Also, breaking up the longer-term goal into more manageable short-term goals can be beneficial and more rewarding. The same principle can be applied to exercise or eating more healthily.

Do one thing at a time. One of the easiest routes to failure is to have too many resolutions. If you want to be fitter and healthier, do just one thing at a time. Give up drinking. Give up smoking. Join a gym. Eat more healthily. But don’t do them all at once, just choose one and do your best to stick to it. Once you have got one thing under your control, you can begin a second resolution.

Be SMART. Anyone working in a job that includes setting goals will know that goals should be SMART, that is, specific, measurable, achievable, realistic and time-bound. Resolutions shouldn’t be any different. Cutting down alcohol drinking is an admirable goal, but it’s not SMART. Drinking no more than two units of alcohol every other day for one month is a SMART resolution. Connecting the resolution to a specific goal can also be motivating, for example, dropping a dress size or losing two inches off your waistline in time for the next summer holiday.

Tell someone your resolution. Letting family and friends know that you have a New Year’s resolution that you really want to keep will act as both a safety barrier and a face-saver. If you really want to cut down smoking or drinking, real friends won’t put temptation in your way and can help monitor your behaviour. Don’t be afraid to ask for help and support from those around you.

Change your behaviour with others. Trying to change habits on your own can be difficult. For instance, if you and your partner both smoke, drink and eat unhealthily, it is really hard for one partner to change their behaviour if the other is still engaged in the same old bad habits. By having the same resolution, such as going on a diet, the chances of success will improve.

Don’t limit yourself

Changing your behaviour, or some aspect of it, doesn’t have to be restricted to the start of the New Year. It can be anytime.

Accept lapses as part of the process. It’s inevitable that when trying to give up something (alcohol, cigarettes, junk food) that there will be lapses. You shouldn’t feel guilty about giving in to your cravings but accept that it is part of the learning process. Bad habits can take years to become ingrained and there are no quick fixes in making major lifestyle changes. These may be clichés but we learn by our mistakes and every day is a new day – and you can start each day afresh.

If you think this all sounds like too much hard work and that it’s not worth making resolutions to begin with, bear in mind that people who make New Year’s resolutions are ten times more likely to achieve their goals than those who don’t.



Mark Griffiths, Director of the International Gaming Research Unit and Professor of Behavioural Addiction, Nottingham Trent University

This article was originally published on The Conversation. Read the original article.