What is the meaning of The Tree of Life (Darwin)?

Question

I am just wondering about the Dates and how they allow enough time for evolution.
The first Sea Mollusk (Sea Shells) 500 million years ago
The first Sea Turtles 350 million years ago
The first man 50 million years ago (Both Homo Sapien and Neanderthal)

I have never heard just how long Evolution is supposed to take, but this does not seem nearly enough time for the complex changes involved.

Does anyone know how long it should take to evolve from Sea Turtle to man?

Answer 1

Darwin tends to use metaphors drawn from organic, rather than mechanical, topics. How does the following crucial passage from The Origin of Species resemble the use of metaphor in nineteenth-century poets such as Tennyson, and novelists such as Dickens and Conrad? (You might wish to compare this passage to another passage quoted in Origin of Species..)

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 each former year 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 tried to overmaster 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 small, 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 all the other branches; so with the species which lived during long-past geological periods, very few now have living and modified descendants. From the first growth of the tree, many a limb and branch has decayed and dropped off; and these lost branches of various sizes may represent those whole orders, families, and genera which have now no living representatives, and which are known to us only from having been found in a fossil state. As we here and there see a thin straggling branch springing from a fork low down in a tree, and which by some chance has been favoured and is still alive on its summit, so we occasionally see an animal like the Ornithorhynchus or Lepidosiren, which in some small degree connects by its affinities two large branches of life, and which has apparently been saved from fatal competition by having inhabited a protected station. As buds give rise by growth to fresh buds, and these, if vigorous, branch out and overtop on all sides many a feebler branch, so by generation I believe it has been with the great Tree of Life, which fills with its dead and broken branches the crust of the earth, and covers the surface with its ever branching and beautiful ramifications (Chapter 4, "Natural Selection").

Answer 2

Darwins Tree Of Life

Answer 3

The Tree of Life shows the interrelatedness between groups of organisms using the length of the branches to indicate the degree of relatedness. The Tree has been designed using calculations of genetic differences. Thus, the Tree is based on actual molecular evidence, and the lengths of the branches are not in dispute.

What has been disputed is the time frame: whether or not molecular mutation rates are fast enough to create the diversity of species within the available time (4.57 billion years). There are a number of theories that may help explain this. But think for a moment about how long a time period a million years is!

Evolution from sea turtle to man is a moot point, because man did not evolve from sea turtles, nor sea turtles from man. They have a common ancestor, which is different. That ancestor may have lived 200-300 million years ago.

Here's what wikipedia says: http://en.wikipedia.org/wiki/Evolution#Molecular_evidence
Also, I recommend Richard Dawkins' book "The Ancestor's Tale"

Answer 4

This Site Might Help You.

RE:
What is the meaning of The Tree of Life (Darwin)?
I am just wondering about the Dates and how they allow enough time for evolution.
The first Sea Mollusk (Sea Shells) 500 million years ago
The first Sea Turtles 350 million years ago
The first man 50 million years ago (Both Homo Sapien and Neanderthal)

I have never heard just how long...

Answer 5

Evolution requires replication with variation. Any process that replicates and has some capability for variation will experience evolution. The "tree" is an effect specifically on life forms and identifies how those life forms changed. The selection process, in the case of life forms, natural selection, allowed some forms to replicate and continue down the evolutionary path while others were culled. The culled ones are the end points on that branch.

Answer 6

Well none of your numbers are correct other than the first one (sort of).... you used scientific nomenclature incorrectly... and people did not evolve from sea turtles....

There were no Homo sapiens 50 million years ago. Humans evolved from mammals which existed long before then (sea turtles are reptiles not mammals).

Evolution takes as long as needed. Either a species adapts to its environment through natural selection - or it goes extinct. Fairly simple process, and it happens much faster than you'd think. Humans of today did not exist just a half million years ago (not all that long geologically speaking) -- evolution is a fairly rapid process because when something is not suited to its environment it dies. The only organisms left are those that are adapted to the environment - and those are the ones that get to breed! We call this evolution...

Answer 7

The thing about sexual reproduction is that you can adapt a species very quickly. You don't have to wait for chance. You pick a suitable mate with the properties needed to survive. Each generation will have a different permutation of genes to try out.

Answer 8

over 490 billion yrs ago was the 1st sign of life.