- Barlow, Connie.
The Ghosts of Evolution.
New York: Basic Books, 2000.
ISBN 0-465-00552-7.
-
Ponder the pit of the avocado; no, actually ponder it—hold it
in your hand and get a sense of how big and heavy it is. Now consider
that due to its toughness, slick surface, and being laced with
toxins, it was meant to be swallowed whole and deposited far from
the tree in the dung of the animal who gulped down the entire
fruit, pit and all. Just imagine the size of the gullet (and
internal tubing) that requires—what on Earth, or more precisely,
given the avocado's range, what in the Americas served to disperse
these seeds prior to the arrival of humans some 13,000 years ago?
The Western Hemisphere was, in fact, prior to the great extinction at
the end of the Pleistocene, (coincident with the arrival of humans
across the land bridge with Asia, and probably the result of their
intensive hunting), home to a rich collection of megafauna:
mammoths and mastodons, enormous ground sloths, camels, the original
horses, and an armadillo as large as a bear, now all gone. Plants
with fruit which doesn't seem to make any sense—which rots beneath
the tree and isn't dispersed by any extant creature—may be the
orphaned ecological partners of extinct species with which they
co-evolved. Plants, particularly perennials and those which can
reproduce clonally, evolve much more slowly than mammal and bird
species, and may survive, albeit in a limited or spotty range,
through secondary dispersers of their seeds (seed hoarders and
predators, water, and gravity) long after the animal vectors their
seeds evolved to employ have departed the scene.
That is the fascinating premise of this book, which examines how
enigmatic, apparently nonsensical fruit such as the osage
orange, Kentucky coffee tree, honey locust, ginkgo, desert
gourd, and others may be, figuratively, ripening their fruit
every year waiting for the passing mastodon or megatherium which
never arrives, some surviving because they are attractive,
useful, and/or tasty to the talking apes who killed off the
megafauna.
All of this is very interesting, and along the way one learns a great
deal about the co-evolution of plants and their seed dispersal
partners and predators—an endless arms race involving armour,
chemical warfare (selective toxins and deterrents in pulp and seeds),
stealth, and co-optation (burrs which hitch a ride on the fur of
animals). However, this 250 page volume is basically an 85 page
essay struggling to get out of the rambling, repetitious,
self-indulgent, pretentious prose and unbridled speculations of the
author, which results in a literary bolus as difficult to masticate
as the seed pods of some of the plants described therein. This book
desperately needed the attention of an editor ready to wield the red
pencil and Basic Books, generally a quality publisher of
popularisations of science, dropped the ball (or, perhaps I should
say, spit out the seed) here. The organisation of the text is
atrocious—we encounter the same material over and over, frequently
see technical terms such as indehiscent used four or five
times before they are first defined, only to then endure a
half-dozen subsequent definitions of the same word (a brief glossary
of botanical terms would be a great improvement), and on
occasions botanical jargon is used apparently because it rolls so
majestically off the tongue or lends authority to the account—which
authority is sorely lacking. While there is serious science and
well-documented, peer-reviewed evidence for anachronism in certain
fruits, Barlow uses the concept as a launching pad for wild speculation
in which any apparent lack of perfect adaptation between a
plant and its present-day environment is taken as evidence for an
extinct ecological partner.
One of many examples is the suggestion on p. 164 that the fact
that the American holly tree produces spiny leaves well above the
level of any current browser (deer here, not Internet Exploder or
Netscrape!) is evidence it evolved to defend itself against much
larger herbivores. Well, maybe, but it may just be that a tree lacks
the means to precisely measure the distance from the ground, and
those which err on the side of safety are more likely to survive.
The discussion of evolution throughout is laced with teleological and
anthropomorphic metaphors which will induce teeth-grinding among
Darwinists audible across a large lecture hall.
At the start of chapter 8, vertebrate paleontologist Richard Tedford
is quoted as saying, “Frankly, this is not really science. You
haven't got a way of testing any of this. It's more
metaphysics.”—amen. The author tests the toxicity of ginkgo seeds by
feeding them to squirrels in a park in New York City (“All the world
seems in tune, on a spring afternoon…”), and the
attractiveness of maggot-ridden overripe pawpaw fruit by leaving it
outside her New Mexico trailer for frequent visitor Mrs. Foxie (you
can't make up stuff like this) and, in the morning, it was
gone! I recall a similar experiment from childhood involving
milk, cookies, and flying reindeer; she does, admittedly, acknowledge
that skunks or raccoons might have been responsible. There's an
extended discourse on the possible merits of eating dirt, especially
for pregnant women, then in the very next chapter the suggestion that
the honey locust has “devolved” into the swamp locust, accompanied by
an end note observing that a professional botanist expert in the
genus considers this nonsense.
Don't get me wrong, there's plenty of interesting material
here, and much to think about in the complex intertwined evolution
of animals and plants, but this is a topic which deserves a more
disciplined author and a better book.
June 2005 