Tagged with evolution

Absence makes the genitalia grow weirder

Absence makes the genitalia grow weirder

Evolution loves penises. How else do you explain all the crazy penis shapes out there? Por ejemplo (slightly nsfw): the corkscrew duck penis, the spiny cat and chimp members, the sci-fi-esque spiked penis of a seed beetle, the 4-headed penis of the echidna, and, well, all of these. Why so many ways to make a sperm … Continue reading

Sex or no sex, that is the question

Sex or no sex, that is the question

There are pros and cons to everything in life, and sex is no exception. From an evolutionary biology standpoint, sex is a compromise (which may explain why so many of our lawmakers seem to be against it). Reproducing asexually means you don’t have to share with anyone else: all your genes get packed into each … Continue reading

The making of a toad, through sex and cloning

The making of a toad, through sex and cloning

At a certain age, children want to know the answer to one simple question: how are babies made? And the answer seems simple enough, too (if sometimes a bit awkward): one sperm plus one egg equals a baby. But this simple scenario breaks down quickly if we look around the animal kingdom (I won’t even … Continue reading

Older worms have more sex appeal

Older worms have more sex appeal

C. elegans are tiny worms that exist as hermaphrodites or rare males. A male rubs against a hermaphrodite with the mating apparatus on his tails and if he thinks she’s sexy enough, he’ll try to mate with her. And what turns on a male worm? Answer: an older lady. No one knows what the male … Continue reading

Save some of that sperm for later

Save some of that sperm for later

In spiders, there are many species where the males only get one chance to pass on their genes. They stop making sperm as soon as they become adults, and after one sexual encounter, their sperm are all used up. In the great game of evolution, this isn’t the best strategy. They’ve quite literally put all their eggs in one basket. … Continue reading

Daughters get cheating gene from Dad

Daughters get cheating gene from Dad

In honor of Father’s day, I have a story about fathers and daughters. Zebra finches are socially monogamous birds. This means that, like humans, they generally form lifetime relationships with a single partner. Also like many humans, they’re known to sleep around. For males, this makes sense, from an evolutionary standpoint. The males can increase … Continue reading

Parasites give snails an incentive for sex

Parasites give snails an incentive for sex

Among the New Zealand mud snail (Potamopyrgus antipodarum), some do it, some don’t. Have sex, that is. Just how many snails live the sexual life is determined, in large part, by how many snails in the population are infected by parasites, according to new research by Kayla King, Jukka Jokela, and Curtis Lively. The findings … Continue reading

Evolution of genes for shorter pregnancy

Evolution of genes for shorter pregnancy

Five studies released this week focus on different aspects of reproduction, from advances in in vitro fertilization, to understanding how genes are regulated during early development (and how this could affect cancer later) and why human eggs are prone to mistakes that cause birth defects, especially in older women. Another study even discovered a way that  stress during … Continue reading