Even small children learn very early that we humans are not the only life here on earth.
But the biology books we had, when I was growing up, didn't have such a clear story on
who the other folks are. There are a lot of basic things that nobody knew about until
just a few years ago... and a lot of things I didn't know about until this week!
I don't have time to try to become a real biologist, but I have tried to understand
what makes us smart -- and that means trying to see who ELSE is smart on this planet.
When I was small, adults would explain -- "there are two kingdoms of life,
the animals and the plants." Sophisticated people would even say: "You can see a lot of animals by going to a zoo. We call it a 'zoo" because it's a place for animals; 'zoa' is just another name for animals."
But then people began to think more about those wiggly single-celled creatures you
can see in a microscope -- the microbes. At first, they asked: "OK, we only have plants and animals. So which of these wiggly little things is a plant, and which is an animal?" Some of them are green and get their energy from light, just like trees. Others, like the amoeba, live their lives like hunters, gobbling up other microbes. But gradually, biologists decided that it would make more sense
to create a whole new category for the microbes, and put us big animals with lots of cells
into a different category. They also decided that fungi (from foot fungus to yeast to mushrooms and more) belong in a different category. That gives four kingdoms of life -- microbes, us big types of animals ("animalia"), big plants, and fungi.
What happens when you live your life with this nice simple four-fold picture, and then suddenly a strange and alien kind of life from outer space shows up and takes over more than half of your planet? Or rather, what if it already took over half your planet, and you didn't even know about it?
That's sort of happened about 10-15 years ago, and a lot of adults still don't know about it.
More precisely -- a famous new guy called Woese showed up, and made us aware of an important form of life called "archaea" (NOT archaebacteria now!). Archaea are really fascinating, and very important to the cycle of life on earth. I am tempted to say a whole lot more about them. But so far as we know, they are all just another kind of microbe -- even though half the weight of life
in the ocean is archaea, and even more deeper under the earth. So far as we know, they aren't smart -- they don't have any intelligence. (But some folks wonder at times what kind of intelligence might be hidden in the connection between the microbes of earth.)
So now -- people mostly say the life on earth is in three DOMAINS -- archaea, bacteria,
and out kind of life, the "eukaryotes." We eukaryotes are made up of the textbook kind of cell --
a cell with an outer wall (a membrane), a nucleus in the middle (containing all or almost all
the DNA), and a bunch of other stuff called "cytoplasm." When I went to elementary school,
everyone "knew" that the cytoplasm was like a ball of water or jelly; now we know that it
is much more interesting, because of all the little tubes and compartments it has inside it,
almost like the inside of a crab. But the bacteria and the archaea don't have a nucleus! They are totally different. In GOOD elementary schools, they now teach "ABE" -- the three domains of life,
archaea, bacteria and eukaryotes. In good high schools, they pay serious attention to all three,
because all three are important to the ecology and environment of earth.
Is there other stuff we should know about, beyond even ABE? What about viruses? Souls? Alien life forms that might exist on other planets? Those are important too, but this little blog will not go beyond ABE. In fact, it will stick to us eukaryotes. That's where all the intelligence is that we know about in biology.
And now -- WITHIN the domain of eukaryotes, we still have the four kingdoms,
the eukaryote microbes ("protists"), the animals like us with more than one cell
("animalia"), the fungi, and the plants with more than one cell. Little hunters like the amoeba
(which can act pretty smart in its own way when it stalks its prey) are still called "protozoa" -- protist animals, but that's all informal. They aren't part of "animalia," our group.
They are animals and they are zoa, but they aren't "animalia."
So what about us animalia? Who is smart in our group?
Us, of course -- at least by comparison with the other guys we can see on earth.
Humans are ONE of the pinnacles of intelligence on earth.
But who are the others?
Of course, we all know about our cousins -- the mice, the rats, the cats, the dogs, the elephants, the dolphins, the whales, the tigers, the orca, the ferrets, and other mammals. The human brain does have at least one special new feature, really basic in nature, beyond what the mouse has... but we're all basically in the same family.
Years ago, I read a very fascinating and important story of evolution, of story of the rising levels of intelligence from the fish to the amphibian to the reptile to the birds and the mammals. It was written by a psychologist called M.E. Bitterman, for Scientific American. Later, in a book edited by
Francis Schmitt, I read a similar story of how the wiring of the brains changed from fish to
reptiles to birds and mammals, showing how brains evolved at the same time intelligence evolved.
Of course, this was all the history of VERTEBRATES -- the big group of animalia which we are part of. And yes, folks, we are the smartest of all of them, and we have a great chain of ancestors
which can help us understand how we got there. I have spent a whole lot
of my life trying to understand that chain.
But is there anyone who is smart who is not a vertebrate?
Many years ago, I actually looked up that guy, M.E. Bitterman, and called him on the telephone.
"have you learned anything more about this great story?" Yes, he had some new papers in Science magazine. Most of it was just proving what he already knew. But there was one startling new development. He took those psychology tests he used, which showed how mammals are smarter than reptiles, and he tried them out on bees. A hive of bees, it seems, is as smart as a mammal, by some crucial tests.
Other folks I met have studied the octopus in their lab - and the legends of its uncanny intelligence really seem to be true.
So last week I thought -- "We have three top smart guys on earth: the human,
the octopus and the ant or the bee. What do I know about where the octopus fits in the story of evolution?" I felt pretty guilty that I never bothered to learn or remember where the octopus fit in
Then when I checked -- I didn't feel guilty. Only in 2011 did the guy win the prize for figuring out the basic story.
We animalia basically come in five kinds: (1) sponges and the like, which are our common ancestor;
(2) eccentric types, the "radialia,' which never got very far; (3) our type, vertebrates plus,
called "deuterostomia" (defined by the way our first mouth turns into an anus, the real key to what we are?); (4) the octupus's type, molluscs plus, called something like "lopotrophia"; (5) the type
which ants and bees belong to, arthropods plus plus, called something like eczema...
So it seems that we actually have three great lineages or chains of intelligence we could study,
eventually... the vertebrate chain, the mollusc chain, and the arthropod chain.
The "plus" and "plus plus" mainly just add earlier stages to the chain, along with a few "never got very far" oddballs. For us vertebrates, there are earlier little wormy guys, " semiverebrates" or "hemichordata", which could help us figure out the pathway to something as advanced as an eel, on the way to the fish. For the arthropods, it seems there are nematode worms. For molluscs... I'm not sure what the relation is to their relatives, the annelid worms, but everyone agrees that the molluscs and annelids evolved from simpler creatures, like "bryzoa," which would just sit there in the water
feeding from floating food crossing the special hairs they use for eating.
The three great chains of intelligence... within three of the Big Five of animalia.
Nice to have the big picture...
but of course, I still don't know what the chain leading to the octopus is like in detail.
I'll still be paying more attention to vertebrates -- except when we keep the artropods
from invading our kitchen, or when we make better use of molluscs in that same place.