Improbable Destinies: Fate, Chance, and the
Future of Evolution. By Jonathan B. Losos. 2017.
Riverhead Books. (ISBN 0399184929). 384 pages.
Early in Improbable Destinies, Jonathan Losos
introduces himself as a teenage reptile nerd, presenting a goofy photograph of his 13-year-old
self. His author’s photograph on the cover end
flap portrays the continuity he feels with that
teenager, as he smiles broadly while a bright green
lizard crawls over his face. His Anolis studies,
which he continues as a Harvard professor, began
with an eighth grade science project.
Losos conveys excitement about the questions posed by living things, the way those questions are pursued by scientists, and the sheer joy
of coming to a deeper understanding of the natural world. In the first three chapters, he poses the
puzzle of convergent evolution, which the anoles
exhibit spectacularly on islands throughout the
Bahamas. Then Losos reminds us of the “
opposite” of convergence with examples of idiosyncratic species. What’s driving these very different
results of evolution by natural selection?
The remainder of the book is divided into
two sections, the first covering research in the
wild, the second in the laboratory. Darwin and
many others feared evolution research was all
but impossible because of their assumption that
the pace of change would be too slow, made of
almost imperceptible steps. But field results began
to show that change could be rapid, measurable
within a scientist’s working lifetime.
With just enough detail, and in an easygoing
conversational style, Losos introduces studies of
the peppered moth, Galapagos finches, Trinidadian guppies, the anoles of the Bahamas, the
amazing plants of the Rothamsted Experimental
Station in England, sticklebacks in British
Columbia, mice in the Nebraska Sand Hills. For
each he tells the story of a scientist or team of scientists, emphasizing how they solved the puzzle
of how to investigate a particular facet of convergent evolution.
The next three chapters take us into the long-running study of E. coli by Richard Lenski at
Michigan State, Michael Travisano’s study of
yeast, and Fred Cohan’s of Drosophila. It’s a
strength of the book that Losos has visited most
of the sites of these research programs, both field
and lab, and has had extensive discussions with
most of the researchers.
Natural selection, as it turns out, leads to
both unique adaptations and parallel adaptations.
If populations start exactly the
same and experience the same
environments, they usually evolve
in more or less the same way.
There is randomness in which
mutations occur, and that randomness will cause populations
to diverge, occasionally a lot, but
usually just a little, as long as they
remain in the environment to
which they’ve been adapting. By
contrast, if they start differently
or experience different events
through time, populations are
more likely to diverge. (p. 282)
The advent of genomic science has permitted a
deeper look into the mechanisms underlying
these varying evolutionary outcomes, with
Even when populations evolve
in parallel, the hidden differences that are accruing may steer
them in different directions
should they be exposed to novel
conditions. (p. 281)
… once the first mutation
changes the folding pattern [of a
protein], the second mutation
would cause disruptive changes
in the new configuration, and
thus the mutations, although indi-
vidually favorable, cannot occur
in combination. It’s like origami:
once you start down the path to
making an elephant, you can’t
change mid-course and make a
goldfish. (p. 302)
… it is so hard to make a priori predictions of evolution at
the genetic level. The genome is
just too big and complicated …
The book concludes with two chapters that
build on the earlier themes. The first looks at implications of these understandings of evolution for
our approach to infectious disease and to competition for resources in agriculture. The second speculates on the question of convergent forms of
intelligent life in the universe. Detailed notes with
references are presented in an engaging way, tied
to the page of the relevant text, with useful comments about resources both primary and popular.
As a striking final image, Losos holds up
Ornithorhynchus for our admiration. The duckbill
platypus is clearly a one-of-a-kind species, yet
each of its famous features, on deeper analysis,
results from an episode of convergent evolution
with a different group. Improbable Destinies
advances our understanding of the mechanisms
at the root of both these trends in evolving species. Losos has written tales of scientists at work,
strategizing ways to extract secrets out of recalcitrant animals and plants, that will entertain and
inform a wide audience for years to come.
Seattle WA 98122
THE HUMAN MIND
The Evolution of Imagination. By Stephen T.
Asma. 2017. The University of Chicago Press.
(ISBN 9780226225166). 271 pages. Hardback.
This book explores a unique feature of
humans: our ability to imagine, to improvise,
and to create the unexpected. Using examples
from music, comedy, philosophy, religion, as
well as exploring concepts from evolutionary
biology, animal behavior, and neuroscience, Stephen Asma attempts to explain this exceptional
human quality. In addition to being a philosopher, Asma is also a jazz musician, and most sections begin by describing some part of the
process of creating music, which was both
understandable, as improvisation is a cornerstone of jazz music and creating music for pure
enjoyment is a rare trait to find in the animal
world, but also slightly grating as it felt like an
overused device. However, as I progressed
through the book, I found myself looking