The old joke about the big-headed bloke in the office compensating for a small package is actually true among a rather raucous species of monkeys.
UK researchers found when there was a single male in a group of howler monkeys, therefore creating greater competition for females, he tended to have larger vocal organs but smaller testes. Generally, the more males there were, the less competition for females, and the bigger the males' balls.
Not only did the loudest howler monkeys have lesser cojones; they also produced less sperm.
The research supported Charles Darwin's notion that there was a balance in evolution between characteristics that are useful in competing for mates and those that are useful in fertilising eggs.
Pumas were using Tinder long before us
Blokes jump at the nearest female; ladies are a little more choosy. Sound familiar?
While websites like Tinder have ripped the romance out of hooking up, New Zealand and US scientists have revealed how pumas were using these straight-forward mating tactics even while Victorian-era couples were fluffing around with courtship waltzes and hanky signals.
Monitoring 39 GPS-collared pumas in California, they found male pumas had a simple strategy of "swiping right" for just about every available female nearby, but the ladies only "swipe" for matches based on more than just looks, size and age.
The most important factor was the number of scrapes - scent-marking locations - created by the male over 90 days of consorting. The study also revealed females often mated with more than one male to intentionally confuse paternity, boosting the kittens' survival chances.
Why our universe is weird
The universe isn't just expanding - it's also now officially weird.
European scientists have just shown how quantum particles at potentially opposite ends of the universe can have an instant effect on each other - a phenomenon Einstein didn't think possible and called "spooky action at a distance".
The researchers have performed a "loophole free Bell test" which suggests Einstein was wrong and throws out the idea that distant objects cannot directly and instantaneously influence each other - the local realism hypothesis.
Scientists set up stations about 1.3km apart and produced photons and electrons in an entangled state.
After 245 successful trials, their results, reported in the journal Nature, effectively disproved the local realism hypothesis.
Poo transplants becoming more popular
Stop reading if you're squeamish - but UK researchers have just reported that faecal transplants are outperforming antibiotics, and are rapidly becoming the treatment of choice to treat severe infections.
Clearly not for the queasy, the procedure involves introducing a liquidised stool, or frozen microbes, from a healthy donor to the bowel of a patient to re-colonise their gut with healthy bacteria.
Gut microbes play a key role in our immune systems and health - and transplanting faecal matter from one person to another is increasingly being used to control severe life-threatening infections such as recurrent Clostridium difficile that kill thousands of people annually.
A review in the BMJ found an 85 per cent success rate with the transplants. In New Zealand, around half of district health boards have treated at least 30 patients this way since it started to be used in 2011.
What makes some areas safer than others?
Having facilities such as schools and medical centres nearby can make a negative difference in neighbourhood crime rates, New Zealand research suggests.
In a study just published in the Journal of Criminal Justice, Otago University researcher Dr Amber Pearson found that "high-risk" neighbourhoods most resilient to crime were more than twice as far away from community buildings than those least resilient but equally high-risk.
Using socio-economic data and neighbourhood-level crime statistics recorded between 2008 and 2010, the researchers put together a national "crime resilience index". Next, they compared the index and neighbourhood characteristics, finding how more crime-resilient areas typically had decreased access to a range of living infrastructure.