Category: Evolution

The deadliest sea snake is actually two look-alike species

By Ed Yong | November 20, 2012 9:00 am




Read More

Q: Why don’t apes have bigger brains? A: They can’t eat enough to afford them

By Ed Yong | October 23, 2012 9:00 am

As animals get bigger, so do their brains. But the human brain is seven times bigger than that of other similarly sized animals. Our close relative, the chimpanzee, has a brain that’s just twice as big as expected for its size. And the gorilla, which can grow to be three times bigger than us, has a smaller brain than we do.

Many scientists ask why our brains have become so big. But Karina Fonseca-Azevedo and Suzana Herculano-Houzel from the Federal University of Rio de Janeiro have turned that question on its head—they want to know why other apes haven’t evolved bigger brains. (Yes, humans are apes; for this piece, I am using “apes” to mean “apes other than us”).

Their argument is simple: brains demand exceptional amounts of energy. Each gram of brain uses up more energy than each gram of body. And bigger brains, which have more neurons, consume more fuel. On their typical diets of raw foods, great apes can’t afford to fuel more neurons than they already have. To do so, they would need to spend an implausible amount of time on foraging and feeding. An ape can’t evolve a brain as big as a human’s, while still eating like an ape. Their energy budget simply wouldn’t balance.

Read More

When competition is intense, viruses spill over into new hosts

By Ed Yong | October 16, 2012 7:00 pm



Read More

CATEGORIZED UNDER: Evolution, Medicine & health, Viruses


By Ed Yong | September 28, 2012 9:00 am





Read More

Why do killer whales go through menopause?

By Ed Yong | September 13, 2012 2:00 pm

Here’s yet another reason why humans are weird: menopause. During our 40s, women permanently lose the ability to have children, but continue to live for decades. In doing this, we are virtually alone in the animal kingdom. From a cold evolutionary point of view, why would an animal continue to live past the point when it could pass on its genes to the next generation? Or put it another way: why don’t we keep on making babies till we die? Why does our reproductive lifespan cut out early?

One of the most popular explanations, first proposed in the 1966, involves helpful grandmothers. Even if older women are infertile, they can still ensure that their genes cascade through future generations by caring for their children, and helping to raise their grandchildren.* There’s evidence to support this “grandmother hypothesis” in humans: It seems that mothers can indeed boost their number of grandchildren by stepping out of the reproductive rat-race as soon as their daughters join it, becoming helpers rather than competitors.

Now, Emma Foster from the University of Exeter has found similar evidence among one of the only other animals that shows menopause: the killer whale.

Read More

Same gene linked to bigger brains of dolphins and primates

By Ed Yong | September 11, 2012 7:00 pm




Read More

Newly discovered rat that can’t gnaw or chew

By Ed Yong | August 21, 2012 7:00 pm



But on the Indonesian island of Sulawesi, Jacob Esselstyn has discovered a new species of rodent that radically departs from this universal body plan: a “shrew-rat” that he calls Paucidentomys vermidax.Its name –a mash-up of Latin and Greek—gives a clue to its lifestyle. It means “worm-devouring, few-toothed mouse”.

Read More

A world of genetic diversity within a single tree

By Ed Yong | August 12, 2012 12:00 pm





Photo by Born1945

CATEGORIZED UNDER: Evolution, Genetics, Genomics, Plants

What the "world's coolest algae" tells us about the reasons for extinction

By Ed Yong | August 8, 2012 9:00 am

Cheetahs have two problems: their numbers are low because their habitats have disappeared over time, and they have very low genetic diversity. Neither factor bodes well for their future, but which presents them with the greatest risk of extinction? This isn’t just an academic question. It’s one with real consequences for conservation, and affects whether breeding programmes should just focus on raising more cheetahs, or should carefully mix and match parents to produce genetically diverse young.

Really, what you want is an experiment that tinkers with population size and genetic diversity independently to see which matters most. And obviously, you cannot do that with cheetahs since they are rare and hard to work with.  And, you know, endangered.

Tim Wootton from the University of Chicago recognised this problem. As he told the audience at the 2012 Ecological Society of America Annual Meeting: “We needed an alternative charismatic organism.” To chuckles, he unveiled his choice: the sea palm. It’s a brown frond-like seaweed that grows on the western coast of North America. Wootton calls it “probably the world’s coolest algae”.

Twelve years ago, he and his wife Cathy Pfister bred sea palms to varying degrees of genetic diversity and transplanted them onto rocky shores in clumps of different size. Yesterday, he presented the results of the experiment. I wrote about the study for Nature News, so head over there to see what happened.

Image by Eric in SF



By Ed Yong | August 6, 2012 12:05 pm

In Nicole King’s lab, a bacterium is making a group of tiny cells stick together. That might seem a little humdrum for a group whose members can build electric grids, create snow, and cripple nations. But King’s bacteria should not be overlooked, for they are recapping one of the most important events in the history of life: the move from one cell to many.

The cells in question are choanoflagellates – the closest living relatives of all animals. They’re not our direct ancestors, but they give us clues about what those ancestors were like when they were still swimming around as single cells. Choanoflagellates normally live in solitude, moving about with sperm-like tails and voraciously eating bacteria. But they can also form big colonies. If we can understand why this happens, we might get hints as to why our single-celled ancestors did the same.

King has now found the answer, and it’s a tantalising one. The solitary cells become sociable after being exposed a molecule called RIF-1 that’s produced by some of the bacteria that they eat. When they divide in two, the daughters normally go their separate ways; add a splash of RIF-1, and they stick together instead.

This raises an obvious question: did bacteria also help the single-celled ancestors of animals to band together? Did they contribute to the evolutionary foundation of every ant and elephant, every fish and finch? “That’s my favourite hypothesis,” says Rosie Alegado, the lead author on the new study. “Animals evolved in seas teaming with bacteria and have been passively exposed to bacterial chemical cues, intended and unintended.” But she cautions that this is still an open question.

Read More

CATEGORIZED UNDER: Animals, Bacteria, Evolution

Discover's Newsletter


Not Exactly Rocket Science


See More

Collapse bottom bar

Login to your Account

E-mail address:
Remember me
Forgot your password?

Not Registered Yet?
