BY DR. JOSE PALU-AY DACUDAO
(Part 4)
AMONG mammals, humans and oceanic dolphins have the largest brain to body mass ratio.
There are numerous theories on why humans have large brains, and elaborating on them would take pages.
In brief, the usual suspects are a lifestyle of hunting, group behavior, tool making (and more). Anatomically modern humans of species Homo sapiens first existed 300,000 thousand years ago, and their brains had begun to approach the 1350 grams often cited as the average for humans.
Caveats: One, Neanderthals (Homo neanderthalensis) had brains at least as large as modern humans. Thus, apparently there are other factors involved aside from brain size.
Two, about 35 thousand years ago, human behavior all of a sudden became more complex, bespeaking of more intelligence. The classic often-cited example is the appearance of cave paintings.
The reasons for this are not clear, as the brain sizes of humans before and after this event are similar. (By the way, there are some theologians that believe that this event marks the point in time when humans received rational souls.)
Three, oceanic dolphins have brains as large or larger as those of humans, and (this has never failed to amaze me) much more convoluted. If we just follow the rule that the bigger and more convoluted brain is the more intelligent one, dolphins should be more intelligent than us. Thus, there are other factors involved aside from the above-mentioned two.
Dolphins are sentient, use tools, exhibit joy and depression, and pass on learned behavior to the next generation which is what culture is. Perhaps dolphins are just as intelligent as us humans, but do not have the opposable thumb that enabled us to build complex tools and civilizations.
I cannot emphasize it less: killing sapient dolphins and whales with brains as large as ours and more convoluted is murder. I even regard killing elephants, which have brain to body ratios approaching ours as murder. (Elephants are an exception to the dumb herbivore idea, but they live in cooperative herds, a lifestyle that needs large brains.)
This leads to an interesting question. We humans have a brain of about 1350 grams. Would deliberately killing a Homo erectus with a brain of about 1000 grams, and is the precursor to Homo sapiens, be murder?
How about maliciously terminating a Homo habilis, which has a brain of about 650 grams and is the precursor to Homo erectus?
Or to take it further, would slaying a member of the Australopithecus with a brain of about 450 grams, the genus that preceded Homo, be murder?
(As a comparison, Pan troglodytes, the chimpanzee, Homo sapiens’ closest extant relative, has a brain weight of about 380 grams. Generally, we humans don’t consider killing a chimp as murder.)
Killing these cousins of humankind cannot of course happen, because they are already extinct. (To be continued)/PN
