THE MISMKASURE O F M A Ncan be ordered onag scale from amoebae at the bottom (p. 175) to
extraterrestrial intelligences at the top (p. 248). I have not encoun-
tered such an explicit chain of being since last I read Kant's spec-
ulations about higher beings on Jupiter that bridge the gap
between man and God.
Jensen has combined two of the oldest cultural prejudices of
Western thought: the ladder of progress as a model for organizing
life, and the reification of some abstract quality as a criterion for
ranking. Jensen chooses "intelligence" and actually claims that the
performance of invertebrates, fishes, and turtles on simple behav-
ioral tests represents, in diminished form, the same essence that
humans possess in greater abundance—namely g, reified as a meas-
urable object. Evolution then becomes a march up the ladder to
realms of more and more g.
As a paleontologist, I am astounded. Evolution forms a copi-
ously branching bush, not a unilinear progressive sequence. Jensen
speaks of "different levels of the phyletic scale—that is, earth-
worms, crabs, fishes, turtles, pigeons, rats, and monkeys." Doesn't
he realize that modern earthworms and crabs are descendants of
lineages that have evolved separately from vertebrates for more
than 500 million years? They are not our ancestors; they are not
even "lower" or less complicated than humans in any meaningful
sense. They represent good solutions for their own way of life; they
must not be judged by the hubristic notion that one peculiar pri-
mate forms a standard for all of life. As for vertebrates, "the turtle"
is not, as Jensen claims, "phylogenetically higher than the fish."
Turtles evolved much earlier than most modern fishes, and they
exist as hundreds of species, while modern bony fishes include
almost twenty thousand distinct kinds. What then is "the fish" and
"the turtle"? Does Jensen really think that pigeon-rat-monkey-
human represents an evolutionary sequence among warm-blooded
vertebrates?
Jensen's caricature of evolution exposes his preference for
unilinear ranking by implied worth. With such a perspective, g
becomes almost irresistible, and Jensen uses it as a universal crite-
rion of rank:
The common features of experimental tests developed by comparative
psychologists that most clearly distinguish, say, chickens from dogs, dogs
from monkeys, and monkeys from chimpanzees suggests that they are