Our cells are packed with various protein-stuffed sacs, each dedicated to carrying out essential tasks. One kind of organelle is peculiar, though. Mitochondria are jellybean-shaped structures whose jobs include making the fuel that our cells use to power everything they do. What makes mitochondria strange is that they carry their own DNA. It’s not a lot of DNA–just 37 genes–but mitochondria can make extra copies of it as they grow and divide. In other words, they act an awful lot like bacteria.
The human brain is, for want of a better word, ginormous. Sure, it’s only about as big as a cantaloupe, but it’s made of the hungriest cells in the human body. Keeping the brain supplied with energy is a huge challenge. In my new column in Discover, I describe how scientists have discovered some of the molecular tricks we’ve evolved to feed our neurological beast. Check it out.
Originally published July 26, 2011. Copyright 2011 Carl Zimmer.
Discover, July 26, 2011
In 1758 the Swedish taxonomist Carolus Linnaeus dubbed our species Homo sapiens, Latin for “wise man.” It’s a matter of open debate whether we actually live up to that moniker. If Linnaeus had wanted to stand on more solid ground, he could have instead called us Homo megalencephalus: “man with a giant brain.”
Regardless of how wisely we may use our brains, there’s no disputing that they are extraordinarily big. The average human brain weighs in at about three pounds, or 1,350 grams. Our closest living relatives, the chimpanzees, have less than one-third as much brain—just 384 grams. And if you compare the relative size of brains to bodies, our brains are even more impressive.
In tomorrow’s New York Times, I’ve got a story about evolutionary biologists who make New York their Galapagos Islands. Working on this story was great fun–I traipsed around Manhattan parks and medians, checking out mice and ants and salamanders. I spoke to other researchers who study plants, fish, and bacteria in and around the city. All of them observe evolution unfolding in what might seem like a very unnatural place. But after four billion years, nothing can stop evolution. Not even New York.
The Times has posted some of Damon Winter’s wonderful photographs for the story along with some audio from some of the scientists I describe. You can also listen to the new podcast, which features the story too (link to come).
[ Photo: Creative Commons: NatalieTracy on Flickr ]
The New York Times, July 25, 2011
To study evolution, Jason Munshi-South has tracked elephants in central Africa and proboscis monkeys in the wilds of Borneo. But for his most recent expedition, he took the A train.
Dr. Munshi-South and two graduate students, Paolo Cocco and Stephen Harris, climbed out of the 168th Street station lugging backpacks and a plastic crate full of scales, Ziploc bags, clipboards, rulers and tarps. They walked east to the entrance of Highbridge Park, where they met Ellen Pehek, a senior ecologist in the New York City Parks and Recreation Department. The four researchers entered the park, made their way past a basketball game and turned off the paved path into a ravine.