Tag Archives: sex evolution

Amoebas revolutionize our understanding of sex

Amoebas caught in the act


Amoebas are the first eukaryotic creatures, they’re about years old, and still exist today, with a myriad of forms and evolutionary tweaks, interspersed with familiar lineages like animals and plants. The general consensus regarding them was that they are asexual, meaning that they just divide on their own and not engage in sexual activities. But now, researchers are forced to rethink that whole idea, after gathering evidence that amoeboid sex.

“It changes how we interpret the evolution of organisms” says study researcher Daniel Lahr, of the University of Massachusetts. “If the last common ancestor of eukaryotes was sexual, then there is in practice no evolution of sex.”

Amoeba sex was probably missed because when they were grown in the lab, they generally didn’t seem to indicate any sexual activity whatsoever, and probably even when they did, the behaviour was labeled as just weird.

“When discussing the sex of amoeboid protists, the existing evidence does not evoke chastity but rather Kama Sutra,” Lahr writes in the paper, published in the March 23 issue of the journal Proceedings of the Royal Society B: Biological Sciences.

It is this reason that made biologists believe that amoebas, all eukaryotes, and subsequently, us, evolved from the same asexual ancestor, but they are now forced to start rewriting some books. The thing with asexuality is that in the short run, it is better; it’s faster, you can do it whenever or wherever you want, without needing any other conditions. But in the long run, it’s not a great idea on its own, as mistakes tend to accumulate in the offsprings, which become weaker and weaker, and eventually die – this is the main reason why sex evolved in the first place. When genomes are splitting and recombining, offspring can shed these mistakes.

“The bring-home message to the biology community: In general, they have to look more widely than they have been if they really want to talk about theories about sex and the roles of sex,” said Fred Spiegel at the University of Arkansas, who wrote a commentary about the study for the same issue. The last common ancestor of all living eukaryotes had to be sexual,” Spiegel conckudes. “Sex is the rule and not the exception.”

Yeah, well, you can just go ahead and insert your jokes about that last remark here.