THE HAZARDS OF THE PAST 
ligence has been developed at the expense of in- 
stinct, and that in the invertebrates instinct has 
been perfected at the expense of intelligence. 
Are we not compelled to adopt what is called the 
monophyletic hypothesis, that is, that our line of 
descent started from one pair, male and female, 
somewhere in the vast stretch of geologic or biologic 
time, and to reason that, had that pair been out of 
the race, we should not have appeared? 
Can we narrow life to a single point, a single cell, 
in the past? Was there one and only one first bit of 
protoplasm? If we were to say that life first ap- 
peared on the globe in Cambrian times, just what 
should we mean? That it began as a single point, 
or as many points? When we say that the primates 
first appeared in Eocene times, do we mean that 
one single primate appeared then? If so, what form 
went immediately before him? This is all a vain 
speculation. 
Does man presuppose all the vertebrate sub-king- 
dom? Was he safe as long as one vertebrate form 
remained? Are his forebears many, and not one 
pair? Can we think of his ancestry under the image 
of a tree, and of him as one of the many branches? If 
so, nothing but the destruction of the tree would have 
imperiled his appearance, or the lopping off of his 
particular branch. Probably all such images are 
misleading. We simply cannot figure to ourselves 
the tangled course of our biological descent. If 
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