4 items which may be useful:
Athanasius "On the Incarnation of the Word", pp.37-38 in Vol.4, 2d Series of
_The Nicene and Post-Nicene Fathers_ (Eerdmans, 1978). The discussion in the
"Prolegomena" to that volume, especially p.lxxi, is helpful.
There is a book of James Barr on the meaning of the tree of life & the concept
of immortality connected with it which was published I think within the last 10 years.
Unfortunately my copy is still inb a box in the basement & I can't remember the title.
(How's that for scholarly reference?)
My own article "A Theological Argument for Evolution" in the ASA Journal vol.38,
March 1986, p.19, addresses this question & offers several possible views.
John C. Munday, Jr., "Creature Mortality: From Creation or the Fall?" (_Journal
of the Evangelical Theological Society_ 35/1, 51, 1992, is a conservative Evangelical
argument "that Scripture does not demand the absence of animal death before the fall."
Hope this is helpful -
George
George L. Murphy
gmurphy@raex.com
http://web.raex.com/~gmurphy/