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Wednesday, Nov. 29, 2006
SCIENCE MEETS METAPHYSICS
Cell findings point to other animals with 'consciousness'
By ROWAN HOOPER
Elephants looking at themselves in mirrors, a humpback whale washed up on a beach north of New York, and a freak dolphin that was caught off Wakayama Prefecture.
These are some of the things I've been thinking about this week, and -- without wishing to come over all Zen -- they've made me think about humans and our relationship to other animals.
And the subject lurking behind all this metaphysical speculation? Consciousness.
First, the dead whale. When neuroscientist Patrick Hof of Mount Sinai School of Medicine in New York got the call asking if he wanted to examine the brain of that whale found dead on the beach, he jumped at the chance. Hof is an expert on a special type of brain cells called spindle neurons, which are only found in the great apes: orangutans, chimps, bonobos, gorillas and humans -- animals distinguished from others by their high intelligence.
Now, you can guess what's coming: Hof found that the brain of the humpback whale contained spindle neurons.
He then found that they are also present in the fin whale and a couple of other cetacean species. Previously thought to be unique to the great apes, spindle neurons have been linked with helping mediate social interactions and transmitting our feelings and emotions in the brain. They might, it is speculated, be what allow us to love. Hof publishes his findings this week in the journal The Anatomical Record.
Spindle neurons probably first appeared in the common ancestor of the great apes about 15 million years ago, but in cetaceans they evolved as many as 30 million years ago, Hof says. This means that they probably evolved independently in the whale species with the largest brains. We have far more spindle neurons than the other great apes, and the whales have a comparable number to us. What does this tell us about their brains?
Cetaceans are probably self-aware. When a mark is stuck on the body of a dolphin such that it can't see the mark, it will position itself in front of a mirror so that it can.
It's not unreasonable to think that whales would do the same -- but finding a mirror big enough to reflect the body of a whale has stopped biologists from doing the experiment.
A large mirror has been found for elephants. When a mark is stuck on their heads, elephants given a mirror will touch their trunks to the mark, passing the same test for self-awareness. When presented with a mirror, most animals -- such as cats, dogs and birds -- do not realize that they are seeing their own reflection. Even "lesser" apes such as gibbons are not self-aware by this measure.
The animals that pass the mirror test have in common the fact that they live in groups. They all have complex methods of communication, they form cooperative units, transmit information culturally -- and several species use tools.
Hof now wants to examine the elephant brain to see if it, too, has spindle neurons. If he finds them, elephants can be added to the select list of animals with these cells once thought to be unique to humans. To me, this strongly emphasizes our evolutionary past and our animal nature. Or should I say that it emphasizes the other animals' human nature?
If other animals have spindle neurons, and if these are confirmed as the cells that allow us to experience such human feelings as love, grief and embarrassment, then what does this mean for animal nature? The question of whether such animals have "consciousness" will not be answered easily, but I think the presence of spindle neurons makes a very strong argument for us to treat them all a bit better.
Which brings me to that remarkable dolphin with an extra pair of fins. It was captured in a "drive hunt" last month off Wakayama Prefecture, the home of the Japanese whaling industry. When the fishermen saw that four-finned specimen among all the others they'd confined in their narrow "killing cove," they forgot about slaughtering it and selling its meat to the supermarkets.
Here was evidence that everyone could see, that dolphins once had four legs and lived on the land. Zoologists who examined the animal said it sprouted the extra limbs probably as a result of a freak mutation that reawoke its distant ancestry. (Like most dolphins caught off the coast of Japan, the four-finned animal was probably chock-full of mercury, but this is probably not responsible for the mutation.)
I don't know if there's the same expression in Japanese, but you sometimes hear people calling each other "animals." There's scorn: "So and so is such an animal"; and disgust at someone's bad manners: "Yuk, you animal!" Sometimes the phrases are inverted, and animals are described with human qualities. Elephant mothers are famous for apparently "grieving" when a young animal dies. Chimps can show apparent jealousy.
In academic discourse it is frowned upon to anthropomorphize like this. We don't know what the animals are thinking, so we shouldn't project our feelings onto them -- whatever they look like.
Fair enough, in academic discourse. As anyone who has spent time with dolphins or chimps will tell you, however, it seems clear that they have feelings and moods -- personalities.
To my mind even if they didn't have personalities, we should treat them and their environments with respect. But not everyone is so soft on animals. If we can make a scientific argument that animals are self-aware, and that some of them are likely to experience grief and maybe even love, it might make a difference to how we treat them.
Killing in Antarctica
Is it too much to hope that the men on the whaling ships that set out from Wakayama's shores to do their killing in Antarctica might think twice before loading their harpoons?
The second volume of Natural Selections columns translated into Japanese has just been published by Shinchosha, at 1,500 yen. The title is "Hito wa ima mo shinka shiteru (The Evolving Human: How new biology explains your journey through life)."