Regarding physical death and the tree of life:
Genesis 3:22 makes pretty clear that the tree of life is the source of immortality. As someone else on this thread also posted, it appears to be the source of immortality for the elect after the second coming.
I believe this conclusively proves that immortality requires supernatural grace, and the tree of life symbolizes that grace. It follows, therefore, that naturally, life is mortal.
BTW, I don't necessarily think the tree of life is literally a tree. I agree with you that it is a symbol for the supernatural grace of immortality.
There is no indication anywhere in Genesis that animals had access to the tree of life before the Fall. It was only in the Garden, and most animals were not in the Garden. So I think it is pretty clear that animals were not given the supernatural grace of immortality before the Fall, or ever.
I don't think there's any reason to believe animal death is evil, or the presence of animal death negates the intrinsic goodness of creation. I stand by my statement that physical death without spiritual death is not evil. Humans cry when someone dies not for the sake of the dead, but for ours. We will miss the person who has passed on.
Regarding randomness and Providence:
I'm not sure what your point is about providence and chaos. If anything, what you say supports the notion that God could have created through evoluton. As you rightly point out, mutations would not be the only way God influences our lives through events that to us seem random.
Regarding the transitional nature of man:
I don't think the assertion that man is "transitional" is scientific, or supported by the evidence. We have, through our intelligence, eliminated nearly all selective pressure on our species. Technology ensures that nearly no one starves before childbearing years. Medical science ensures very few people die of disease before such time. And monogamous marriage virtually insures nearly everyone who reaches reproductive age gets to reproduce. Being good looking helps in getting a good looking mate, but even the ugly usually end up finding someone.
The result is that our species is not likely to change very much, if at all, for a very long time.
I think you're right that more than human rights are grounded in more than just our soul. Our rationality has much to do with it as well. I don't see how the fact that we are biologically related to other creatures negates any of this.
Thanks for pointing out the relevant chapter of Descent of Man. I actually haven't read this book. I am only familiar with the Origin. While it is disturbing that Darwin had some musings that eerily forshadow the ideas of the social Darwinists, it really isn't relevant to whether biological Darwinism is true or not.
Darwinism was a scientist, not a prophet, and his books are not sacred scripture. We are perfectly free to accept from them what is valid and throw out what is erroneous, just as we do with the works of other scientists like Newton, Einstein, and Oppenheimer.
I agree that there is a danger of biology "breaking down the barriers of descriptive and prescriptive." We're already starting to see it in the human cloning and stem cell debate.
However, I don't think that denying the findings of modern science is the best way of fighting those who would attempt to draw erroneous ethical conclusions from it. That just makes you look ignorant and backward.
Rather, the best way of fighting such things is by embracing the descriptive findings of science and then emphsizing that science cannot be prescriptive. There are plenty of principled scientists, like Stephen J. Gould, who strongly support this view and will fight for it as vigorously as any clergyman.
Science and religion need to be united in order to defeat the forces of nihilism.
First, I don't think it's possible to make an honest distinction between Darwin and the Social Darwinists. One of my former profs, Edward T. Oakes, SJ, who has also written some devastating criticisms of the Intelligent Design movement, has a review of the sensationalistically-titled academic history "From Darwin to Hitler" in a forthcoming issue of First Things.
Secondly, I would sound a warning against believing that scientific theories are neutral things in themselves and do not reflect any cosmologies, politics, and so forth of the scientists who put them forward. What's more, they also shape any succeeding cosmologies or politics. The State of Nature theory which is one of the bases for Classical Liberalism reflects a Newtonian cosmology brought down to the political level. Locke himself was a buddy of Newton. Much of modern democracy and indeed modern intellectual inquiry takes as its inspiration Einstein's reflections on relativity and different observers' frames of reference. And I'd bet Einstein himself got some of those ideas from Kantian philosophy.
On interpretations of Scripture, there are also other timebomb passages, like the last lines of Genesis 1 that declare that no animal, including man, was given the right to eat meat, and I seem to recall that Isaiah's prophecy of the Lion lying down with the lamb is generally interpreted to be a recapitulation of the Garden of Eden as well as a foreshadowing of the Kingdom of Heaven.
Humans cry when someone dies not for the sake of the dead, but for ours. We will miss the person who has passed on.
This reduces crying to an excercise in self-referential masturbation. Why did Jesus weep for Lazarus?
The result is that our species is not likely to change very much, if at all, for a very long time.
How long is "very long"? Evolutionary change takes place over hundreds of thousands of years. Are you saying that mankind is now mostly immune to such history? Science and religion need to be united in order to defeat the forces of nihilism.
Arguably, the contemporary conception of science has inspired contemporary nihilism. The upcoming Oakes review I mentioned above reflects on Nietzsche's debt to Darwinism, and decades before either thinker John Stuart Mill advocated allowing "experiments in living" by applying "scientific" methods to social order and morals. Also, since science is incredibly provisional and religion is not supposed to be provisional but dogmatic, there is definitely a big tension in any alliance of both against nihilism.
Nihilism is based on the idea that human will endows the universe with meaning. This isn't a far cry from nominalism and the other anti-essentialist habits of thought that undergird the dominant philosophy of science, not to mention much of modern atheism.