Killer Whales and Menopause

Amongst mammals, only humans, orcas (killer whales) and pilot whales experience menopause. That is, they’re the only mammals whose females stop being able to give birth while they still have decades left to live.

That’s pretty weird. Why wouldn’t evolution select for animals that continued to keep breeding? Wouldn’t that give them the best chance of survival?

Not always. New research by the Universities of Exeter and Cambridge show that these three groups of animals have social structures that – while different – share dynamics that means a female’s offspring stand a better chance of surviving if they stop trying to have new ones and focus on supporting the family they’re already created. In orcas, pilot whales, and us, a grandmother role is an advantage to those who are genetically related.

What good are wasps?

The other day one of my pals, Melanie*, tweeted a question that was being pondered in her workplace: is there any point to wasps? That is, do they seem to serve any useful purpose in nature? The feeling around the office was that they were a stinging nuisance and nothing else, and they wondered why evolution wouldn’t have weeded them out.

I’d first like to point out that this isn’t a correct interpretation of evolution. “Evolution” implies natural selection based on genetic changes: that is, somewhere an oak tree has a gene that makes its bark a little thicker than other oaks, which helps protect it against parasitic insects, which means it stands a better chance of surviving than other similar trees, which means its offspring have a better chance of being produced, which means they’ll also have thick bark, and they out-compete other trees and thrive. While it may typically be true that plants and animals all seem to have their place in nature it’s a romantic falsity to presume that everything evolves to some “purpose”. Things either thrive and reproduce or they don’t, and get selected or deselected. So wasps don’t need to have “a point” to existence; they only need to be able to thrive better than anything else which competes against them.

But I’ll get off that slightly pedantic high horse now.

The point is that wasps actually do have purposes; that is to say, there are things they do that are useful to other organisms than themselves. Lots of animals – as was pointed out in a book called Does Anything Eat Wasps?do eat the little stinging buggers. Wasps are garden pollinators, and eat garden pests like aphids. Some species are very good at pollinating figs. And some not only kill lots of pest insects, but – due to their simple DNA structure – mayhelp scientists research pest controls, medicine, and genetics.

Wasps do good stuff, believe it.

A wasp takes a caterpillar as food for its larvae. Photo from cotinis via Creative Commons license

*This is her real name. Her real, full first name. I wanted to point out that I did not call her “Mel”. I’m sure her mother will be pleased.

Darwin’s 200th birthday


On this day 200 years ago Charles Darwin was born. Why not listen to this celebratory podcast from Scientific American? Or read this op-ed piece in the New York Times?

Or, if you’re anywhere near Chicago, get down to the annual meeting of theAmerican Association for the Advancement of Science, the biggest scientific conference in the world. They have some free events, and Darwin and evolution will be big topics this year along with climate change.

Charles Darwin and the Tree of Life: David Attenborough’s not done with science broadcasting yet!

While some parts of the world watch that lamest of top-tier sporting events, the Superbowl, Brits should be spending their Sunday evening watching David Attenborough’s latest show, Charles Darwin and the Tree of Life.

In this programme, David Attenborough asks three key questions: how, and why, did Darwin come up with his theory of evolution? Why do we think he was right? And why is it more important now than ever before?

2009 is the 200th anniversary of the birth of Charles Darwin and the 150th anniversary of the publication On The Origin Of Species.

Tom Feilden’s blog says what we all think: Attenborough’s a national treasure, and we’re glad that he’s not done explaining the wonders of nature to us.

A few science items…

…some of which I’ve touched on before.