Download Book Review Evolution in 4 dimensions

Review of ‘Evolution in four dimensions: Genetic, Epigenetic,
Behavioral and Symbolic Variation in the History of Life.
Revised Edition 2014. By Eva Jablonka and Marion J. Lamb. MIT Press.
Evolutionary studies tend to be seen as arcane and marginal in the mainstream
press, and an evolutionary perspective is seldom alluded to in understanding
the trajectory of myriad of sensationalised episodes that are presented as the
story of the progress of mankind, at least in the western media. Our attention
is constantly drawn to new and apparently surprising stories that illustrate
depravity, technological breakthroughs and political realignments as if there
was no plot or discernible direction in our continuing narrative of life on this
planet. And yet such modern syntheses of evolutionary thought, as typified in
this book, can show us that there is an underlying build-up of complexity in our
progress and our relationship with the natural world that makes life both more
comprehensible and predictable.
The book, then, I feel, is very timely, pulling together disparate lines of enquiry
to present a fairly comprehensive overview of what now may be considered
the main processes in evolutionary change and development, uncovered since
the new synthesis of evolutionary thought in the 60s and 70s. In doing so, the
authors realise that they are challenging seemingly long-established principles
in evolutionary science and especially the simplified version of genetic
inheritance that is fed to the public.
Their starting point is a statement of four new principles:There is more to heredity than genes
Some hereditary variations are non-random
Some acquired information (including behavioural tendencies) is
inherited
Evolutionary change can result from instruction as well as selection.
In the first section on new developments in genetic research, they examine
how research shows that inheritance of characteristics through genes is more
complex than is usually presented, in that much of DNA is not just a ‘blue print’
for cell production, but behaves in ways to control the bits that do produce
cells, and control the developmental process that can make them flexibly
responsive to the environmental conditions of their growth. Thus genetic
variation is not as random as once believed.
They then go on to explain how epigenetic factors influence development
processes too. This section is more controversial in that they reopen an
argument that many thought was over a long time ago – between Lamarckian
ideas of acquired characteristics being inherited, and the Darwinian natural
selection of random mutations being inherited. Modern research shows the
picture is more complex and there are processes that influence gene activity,
cell structure, methylation and RNA interference which affect information
transmission between cells and are heritable, affecting variations down
generations.
In the third section, they focus on recent research on Behavioral Inheritance
systems – behaviour-influencing substance transmission (e.g. through breast
milk), non imitative social learning, and imitation. Together these are
indicative of a much wider definition of cultural evolution which can also then
be seen to have evolved in a much wider range of organisms than just humans
– to which the term has mostly been applied, certainly in psychological circles.
Transmission of ‘traditions’ become cumulative and lead to evolving ‘new’
lifestyles in a wide range of species.
In the fourth section on Symbolic Inheritance Systems, they finally begin to
relate all the previous ideas to the matter of what are the most important
factors that make humans unique in nature – the way we organise, transfer
and acquire information being crucial, using words and symbols. They review
models that have been previously proposed: memetics and massive modularity
of the mind, both of which tend to focus on ‘selection’ in cultural evolution.
They emphasise the developments in culture through functional adequacy of
artefacts and behaviours in response to the environment and the changing
environments of later generations which may lead to changes to the
transmitted traditions and artefacts handed down. This perspective thus also
encompasses the idea of ‘niche creation’ and the changes that this makes to
the selection pressures on subsequent generations. This can have runaway
effects as seen in the evolution of the peacock’s tail and display on a genetic
level, but at the cultural level in the increasing rates of technological
development in mankind.
The second half of the book is then focussed on how the four dimensions of
evolution interact, perticularly on environmental effects, eg: heat shock and
other forms of genetic damage, which induce changes in gene products and
developmental processes that can explain trends in evolutionary change that
have thus far been inpenetrable, eg: genetic assimilation. This is the
mechanism, recently established, where elements of behavioural sequences,
eg: song, or elaborate nest building are built over evolutionary time by some
elements becoming innate in genetic terms, and are then elaborated by
further learned elements. This has great explanatory value in showing how
Niche Construction becomes stretched by such a process to become very
complex seqences of interaction where the niche constructed increasingly
controls the immediate environment which affects and controls the selection
pressure that impinge on the organism, eg: beaver dams and agricultural land
use in humans. This causes, over time, exponential development processes,
with exponential increases in capabilities. Thus the activities of one generation
influence and shapes the conditions of the next generation, creating feedback
between the inherited genes and the inherited niche, for example in the
spread of lactose tolerance into adulthood that has followed domestication of
cattle and other livestock.
They use this framework to also explain the evolution of language from
primary gesture and sounds found in many species of primates to the
increasingly complex sophistication of the organs of perception that have led
to the complex construction and rapid modulation of sound that constitutes
the ability to produce and understand speech in modern humans. This has
subsequently gone on to underpin the creation of culture that has accelerated
social and cooperative coordination of groups into bands, tribes, societies and
nations, where pressure increasingly selects for better memory, social
awareness of others and their motives, rapid problem solving cognitive
capabilities etc.
The final comcluding sections of the book are devoted to explaining how and
why the previously proposed mechanisms of inheritance have evolved through
elaboration of the products and mechanisms of maintenaance of earlier
heritability systems, including reactions to stress and changing environments
of geography, seasons and climates.
Overall, though it is a densely worded scientific tome at heart, the essential
message, and the pace at which they explain it are sufficiently interesting,
important and ground breaking to keep the reader enthralled. For the more
devoted evolutionary enthusiast, it covers major break throughs in theory and
it's empirical support over the last twenty years or so all in one lengthy, but
intelligible, read – a feat well worth doing, I feel.