The Human Evolutionary Tree
Darwinius masillae - Ardipithecus ramidus
Origins of Mankind
Since Darwin's publication of his "Origin of Species" there has been a increasingly widespead acceptance, particularly in the
secular 'west',
of the idea that Mankind 'evolved' from earlier forms of life that were,
long, long, ago
more like lemurs or monkeys than Human Beings.
This graphic shows such a popularly accepted Monkey to Man progression.
The scientific view of the origins of species, which has contributed to the secularisation of the west by inherently
posing difficult questions to faith, holds that there were many naturally occuring changes in physique and behaviour - some of
these proved beneficial in terms
of survival - and were locally reinforced by such "successes-in-survival" allowing several branching divergences,
based on these survival-favouring changes,
to produce an evolutionary tree of related species - including mankind!
The following graphic demonstrates something of the Darwininian / Scientific approach to describing the Human Evolutionary Tree.
Source : The National Museum of Natural History - Washington, D.C.
Science holds that existing primate species can be divided into six subgroups: lemurs, lorises, tarsiers, New World monkeys, Old World monkeys,
and apes and humans.
Science further holds that the changes that allowed Humans to feature as part of a primate / human evolutionary tree, and which allowed Humanity
to become established as
we know it today, were very slowly accumulated due to various "survival advantages" that these changes
conferred allowing their possessors to be more generally successful in the struggle for life but particularly
so in the gaining of foodstuffs to nourish themselves, their families, and their friends.
The concept of a Human Evolutionary Tree is itself very directly related to more generalised Tree of Life concepts which lie at the heart
of Darwinian Evolutionary
Theory.
As early as July 1837 Darwin opened a notebook to record his thoughts on "that mystery of mysteries - the origin of species" as this entry from
his diary
relates:-
In July I opened my first note-book for facts in relation to the Origin of Species, about which I had long reflected, and never
ceased working on it for the next twenty years.
The direction of the development of Darwin's thoughts can perhaps be illustrated by this famous
Tree of Life sketch from his Notebook B dating from 1837-8:-
Charles Darwin's early evolutionary theory insight of how a branching tree-like genus of related species might
originate by divergence from a starting point (1) to effectively establish related species at such notional points as A, B, C and D.
There is an accompanying text annotation that reads:-
I think
Case must be that one generation then should be as many living as now. To do this & to have many
species in same genus (as is) requires extinction.
Thus between A & B immense gap of relation. C & B the finest gradation, B & D rather greater
distinction. Thus genera would be formed. — bearing relation (page 36 ends - page 37 begins)
to ancient types with several extinct forms.
From Darwin's notebook B now stored in Cambridge University library.
Although Charles Darwin formed his initial evolutionist hunches in or around 1837 his most famous work on the
Origin of Species was not published until 1859.
His chapter summary to "Chapter IV. Natural Selection" in the Origin of Species features this - Tree of Life - related assertion:-
The affinities of all the beings of the
same class have sometimes been represented by a great tree. I believe this
simile largely speaks the truth. The green and budding twigs may represent
existing species; and those produced during former years may represent the
long succession of extinct species. At each period of growth all the
growing twigs have tried to branch out on all sides, and to overtop and
kill the surrounding twigs and branches, in the same manner as species and
groups of species have at all times overmastered other species in the
great battle for life. The limbs divided into great branches, and these
into lesser and lesser branches, were themselves once, when the tree was
young, budding twigs; and this connexion of the former and present buds by
ramifying branches may well represent the classification of all extinct
and living species in groups subordinate to groups. Of the many twigs
which flourished when the tree was a mere bush, only two or three, now
grown into great branches, yet survive and bear the other branches; so
with the species which lived during long-past geological periods, very few
have left living and modified descendants.
The Human Evolutionary Tree, seen from this 'Darwinian' perspective, becomes rather a branch of a mind-blowingly ancient general Tree of Life.
In his work of 1859, issued as it was into a fairly faith-accepting victorian England, Darwin avoided
speculating that Human Beings were themselves subject to evolutionary processes.
Nevertheless, despite much controversy, the view that Humans also 'evolved' gradually gained an increasing acceptance - with consequences
for religious belief - as scientifically inclined contemporaries such as Thomas Henry Huxley ventured to explicitly suggest,
(in his Evidence as to Man's Place in Nature published in 1863), that Human Beings
were themselves a species that was itself closely related to some ape species.
Darwinism and Evolutionary Science in the west has now very substantially accepted, for well over a century, that Humans
have 'evolved' and that there is a Primate / Human evolutionary tree of closely related species.
New Evolutionary tree for Primates (and Humans)
Credit: © The Field Museum, D. Quednau.
As reported in an article in the well-respected scientific magazine "Nature" in April, 2002 on the basis of studies sponsored by the Chicago based Field Museum
the scientific view of the origin of primates has been pushed back from 65
million years ago to 85 million years ago - this is before the dinosaurs became
extinct.
In terms of the Primate / Human evolutionary tree there are a couple of rather interesting concepts. That of
a so-called - earliest common ancestor - of all the primates, (dating from some 85 million years ago), and that of a so-called
- last common ancestor - of apes and humans, (dating from more than 7 million years ago).
The researchers at the Field Museum went so far as to speculate a little on the possible characteristics of the earliest common
ancestor.
According to Dr. Martin vice president of academic affairs at The Field Museum and co-author of the research, who has studied primate evolution from
many different perspectives for the past
30 years, their 85-million-year-old early common ancestor of the primates probably looked like a primitive, small-brained version of today's
dwarf lemur.
That animal would probably have been a nocturnal, tree-living creature weighing about 1-2 pounds, with grasping
hands and feet, also used by the infant to cling to the mother's fur. It probably had large forward-facing eyes
for stereovision and a shortened snout. It would have inhabited tropical/subtropical forests, feeding on a mixed
diet composed mainly of fruit and insects. Like humans, it probably had a slow pace of breeding characterized
by heavy investment in a relatively small number of offspring.
The illustration above left was prepared by Nancy Klaud to accompany the Field Museum's research findings.
Two significant fossil discoveries that were newly, and somewhat triumphantly, announced in 2009 were both seen by the scientists studying them
as having much to offer in terms of throwing light on the human evolutionary tree.
In May 2009 the general public - around the world - first heard of a primate fossil dating from some 47 million years ago,
(and hence from a time quite close to the 'earliest fossil primates' as suggested in the Field Museum study):-
Darwinius masillae
At the high-profile launch ceremony in New York where Darwinius masillae was formally announced comparisons of cultural importance
for this fossil were made with the Mona Lisa and to the Moon Landings.
During the proceedings at the American Museum of Natural History Dr. Jorn Hurum who oversaw the project said:-
"It is the scientific equivalent of the Holy Grail. This fossil will probably
be the one that will be pictured in all textbooks for the next 100 years."
(It has to be said however that in October 2009 other scientists put their own case suggesting that Darwinius masillae had
more in common with the Lemur and Loris branchings of the evolutionary tree than with Apes and Humans).
More on the Darwinius masillae / Ida fossil discovery
pictures - images - background story
Similarly, in October 2009, the general public - around the world - first heard of another significant primate fossil discovery dating from
"as recently" as 4.4 million years ago:-
Ardipithecus ramidus
Interestingly, the discovery and analysis of the Ardipithecus ramidus fossils has caused science to question the previously accepted Monkey-to-Man progression
from a so-called last common ancestor species as this quote from one of the principal researchers involved in the Ardipithecus ramidus study
makes clear:-
"A lot of people were happy to hypothesize that as you went back, into that first half of human evolution since the last common ancestor, as you found these
fossils they’d be increasingly chimpanzee-like,’’ said Tim White, a paleontologist at the University of California, Berkeley,
“We have something getting pretty close to it in time, and it turns out it doesn’t look chimpanzee-like; it’s an unexpected combination of characteristics, some of
which are new in evolution and put this pretty firmly on our side of the family tree, and some others that are very primitive."
More on the Ardipithecus Ramidus Ardi fossil
human evolution missing link pictures images
At age-of-the-sage we are more truly interested in the
Origins of Human Psychology
and Spirituality
than in the origins
of Human Physique!
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