546 EVENING DISCOURSES. 
What were the facts which guided Haeckel in the construction of his great tree 
of life? Let us confine ourselves to his terminal primate branch. Why does he 
represent man and the African anthropoids as springing as terminal twigs of the 
same stem? It was because of the multitude of structural points they had in 
common. He presumed there was only one way in which this community of structure 
could be explained, namely, as an inheritance from a common ancestor. He did not 
believe that animals pursuing separate evolutionary ascents could come hy a complex 
of identical structural modifications. In constructing his tree he made no allowance 
for parallelism or convergence. In brief, he fashioned his tree so that it gave a satis- 
factory explanation of the resemblance and differences which anatomists found when 
they compared men with great anthropoids, great anthropoids with small anthropoids 
or gibbons, gibbons with old-world monkeys, old-world monkeys with new-world 
monkeys, and new-world monkeys with the riff-raff which make up the lowest and 
oldest primates. 
He found it necessary, in order that his tree might give a rational explanation of 
anatomical fact, to make another very important assumption, namely, that the 
evolutionary stages through which man has ascended from the lowest place to the 
highest place amongst primates were still represented by living forms. The human 
was the final and highest stage ; it had evolved from a great anthropoid stage, now 
represented by the gorilla, chimpanzee and orang; the great anthropoids had arisen 
from a small anthropoid stage—the gibbons and siamang—being modified descendants 
of this ancient stage. Still older in type were the monkeys of the old world; the 
monkeys of the new world represented a still earlier evolutionary stage. 
We must recognise, then, that Haeckel constructed his family tree merely as a 
working hypothesis to explain the distribution of structural characters in the higher 
primates. Modern students of culture are familiar with the principles which guided 
Haeckel in framing his pedigrees. As they trace the civilisation of modern Europe 
backwards in time they recognise a series of stages which links our culture with that 
of our paleolithic ancestors. But suppose nothing was known of these buried stages, 
could they not be inferred by a study of the culture of native and backward living 
peoples ? It was by an analogous process of legitimate inference that, Haeckel built 
up the stages which transferred the lowest into the highest form of primate organisa- 
tion—stages which led from a half ape to a whole man. At a later date Haeckel 
counted twenty-six stages in the evolution of man, but at the date of which I speak 
he was content with ten. I need mention only three—the eighth or prosimian, the 
ninth or catarrhine, and the tenth or tailless (anthropoid) stage. It was Haeckel 
who first demarcated man’s evolution into stages. 
T have spoken of the family tree which Haeckel constructed to explain the structure 
of man, anthropoids and monkeys, as a mere hypothesis. How could he have 
converted this, a supposititious history, into a true history 2? Very simply; by finding 
the fossil remains of the missing links—many thousands in number ; the links which 
joined man and the great anthropoids to a common ancestral series ;_ the links which 
joined this upper series to that which gave birth to the small anthropoids ; the links 
which joined the small anthropoids to the ancestral chain from which the monkeys 
of the old world sprang and the still older series which joined the old-world stock to 
that of the new world, and the new-world monkeys to the prosimiae. We have now 
a number of these missing fossil links to guide us in pedigree building, but Haeckel, 
in the year 1866, could cite very few of them. Neanderthal man had been discovered, 
but his relationship to races, past and present, was an unsolved problem. Fossil 
remains of a great anthropoid (Dryopithecus) and of a small anthropoid (Pliopithecus) 
had been discovered in the miocene deposits of Europe. Such discoveries assured 
him that both small and great anthropoids were in existence at this phase of the 
Tertiary history of the earth. Then in the eocene or earliest phase of the Tertiary 
period there were numerous fossil remains of very early kinds of primates representing 
prosimian or pre-monkey forms. Scanty as the geological record then was, it assured 
him (1) that true monkeys had not come into existence at the beginning of the Eocene— 
the first phase of the Tertiary period ; (2) that both small and great anthropoids were 
in existence in the two later phases of the Tertiary period—miocene and pliocene ; 
(3) there was no certain evidence of the existence of man until well into the Quaternary 
period, which in modern phraseology is made up of the pleistocene and recent. 
Now no pedigree or family tree has any scientific value unless it is dated, that is, 
drawn against a background of time. Haeckel boldly drew his family tree against 
the background of time provided by the geological calendar of his day. He depicted 
