Marc Verha
Thu, Jul-13-06, 06:23
K.Wessen 2005 "Simulating human origins and evolution" CUP
http://www.palarch.nl/Non_scientific/review_Wessen_05.pdf
... Ken Wessen really force us to be skeptical about our
human lineage. The amount of fossils placed on the surviving
lineage, was consistently over exaggerated in all
simulations. Personally, I think this reflects on all
science publications revealing yet another missing link in
our evolutionary past. Sadly, the truth apparently is that
most of these so called ancestors our not our 'mothers' or
'fathers', but far more likely our 'second cousin twice
removed'. ...
http://allserv.rug.ac.be/~mvaneech/outthere.htm
http://allserv.rug.ac.be/~mvaneech/Symposium.html
http://groups.yahoo.com/group/AAT
_________
When I first started reading this book, I expected it to be
full of simulations of well known theories, such as the 'Out
of Africa' model versus the 'multi-origin' model or an
estimation of the time for Eve. I expected the computer models
described in the book to be used to test these theories or to
describe some new theories based on the outcomes of these
models. However, it soon became clear that this was not the
case. Instead of claiming to have yet another 'fail proof'
method to reconstruct our human origins, Ken Wessen wants no
more than to use simulations to investigate the effects normal
day to day decisions can have on the evolutionary lineage of
humans. The decision you may make some day or have already
made to move to another country or to marry this person
instead of that, such decisions can change what our
descendants will look like in the far away future. In his
book, he simulates the evolution of populations by varying
migration, mating strategies, population demographics and
fossilization to investigate the pitfalls of reconstruction of
evolution. The book is divided in two different parts,
depending on the description of two different simulation
programs (downloadable from his website). In the first
simulation, called 'Specialist', the emphasis is on the
problems of reconstruction of relatively simple lineages. For
the mathematicians, he gives a detailed description of the
mathematics used to make the calculations necessary to find
the most recent common ancestors, to determine which fossils
are from surviving lineages and the accuracy of the
reconstructions. For the non-mathematicians, I recommend to
skip these parts and move on to the explanations of the
results, since that is completely comprehensible without the
mathematical background. I should mention here that the
presentation of the results is rather dry. Simulation follows
simulation and points are made in percentage of right and
wrong. Important here is to focus on the message. What the
different mathematical approaches to reconstruction of the
lineages clearly show, is that though not one of the
approaches is completely wrong, none of them is completely
right either. The biggest problem is of course (and I think we
could all guess this) the fossilization rate; the more
fossils, the more accurate the reconstruction will be.
Unfortunately, in real life, fossilization is rare. Therefore,
the results presented by Ken Wessen really force us to be
skeptical about our human lineage. The amount of fossils
placed on the surviving lineage, was consistently over
exaggerated in all simulations. Personally, I think this
reflects on all science publications revealing yet another
missing link in our evolutionary past. Sadly, the truth
apparently is that most of these so called ancestors our not
our 'mothers' or 'fathers', but far more likely our 'second
cousin twice removed'. Still, this is not shocking news to
most of the experts in the field. Another implication made
clear in the book is that the demographics of a population as
well as migrations can also distort the picture of the
reconstructed tree. For example, if we want to find the most
recent European common ancestor, we would not think of looking
for it in let 's say China. However, if the most recent
European common ancestor was a member of a more widely
dispersed population, it could very well be, that due to the
small fossilization rate, the closest fossilized specimen of
this population will be found in China, and not in Europe! And
I think we can all guess what the effect of a population
bottleneck would be on the variation in following generations.
After having disillusioned his readers in the first part of
the book by showing the amount of guess work in reconstructing
lineages, the author moves on to the second simulation, called
'Genie'. With this program, he investigates the influence of
different life decisions in the development of a species.
Factors are for instance: population size, migration, mating
strategies (monogamy, polygyny and polyandry), sex ratio,
mating probability (100% for every female that can mate with
every male), fecundity, infidelity and selection. This part of
the book is somewhat more difficult to follow, because the
figures are less easily interpreted as the trees in part I.
Again, the author starts with describing the mathematics
behind the simulations, so you can either read or skip that
again as previously. In this section, the author simulates
evolution, with the aim to investigate the influence of
above-mentioned factors on the survival of different mutations
in two paternal (Y-chromosome), two maternal (mitochondrial
DNA) and two autosomal genes. For every simulation, the
paternal, maternal and biological common ancestors are
determined, if possible, for three populations, as well as the
common ancestors for all these populations together. Again,
the different parameters can give a great deal of different
outcomes, based on chance (a single simulation can be very
different for the average results of 1000 simulations, and as
we know, evolution only happens once), but also on the
relative timing of events. For instance, immigrants from
another population have a more pronounced effect on the
population they migrate into, when they arrive just after a
population bottleneck. It is also possible that only males
migrate (think of Viking settlement in England) or only
females (for instance abduction of the women after a raid, or
simply marriage, since in most cultures the women go and live
with the husband's family). In summary, the simulations show
the wide variety of outcomes when normal factors in life are
taken into account. This makes it painfully clear, that any
reconstruction of the human lineage will have to take all
these factors into account as well as the times when they
occurred. Therefore, after reading this book, I understand why
the author is so reluctant to include any examples of current
theories in his simulations. In conclusion, Ken Wessen has
made very interesting computer simulations to investigate the
effects of a great number of factors on the evolutionary
development of species. This book is a good read for everybody
with an overly optimistic view of our knowledge of human
history. It is a bit of a shame that the book reads a little
bit like a manual. However, what he describes was, for me at
least, an eye opener and I think his simulations are very
valuable to the field of evolutionary science in general, not
just for human evolution. In fact, human evolution may be the
most problematic, if maybe most appealing, field for which
these simulations can be used.
http://www.palarch.nl/Non_scientific/review_Wessen_05.pdf
... Ken Wessen really force us to be skeptical about our
human lineage. The amount of fossils placed on the surviving
lineage, was consistently over exaggerated in all
simulations. Personally, I think this reflects on all
science publications revealing yet another missing link in
our evolutionary past. Sadly, the truth apparently is that
most of these so called ancestors our not our 'mothers' or
'fathers', but far more likely our 'second cousin twice
removed'. ...
http://allserv.rug.ac.be/~mvaneech/outthere.htm
http://allserv.rug.ac.be/~mvaneech/Symposium.html
http://groups.yahoo.com/group/AAT
_________
When I first started reading this book, I expected it to be
full of simulations of well known theories, such as the 'Out
of Africa' model versus the 'multi-origin' model or an
estimation of the time for Eve. I expected the computer models
described in the book to be used to test these theories or to
describe some new theories based on the outcomes of these
models. However, it soon became clear that this was not the
case. Instead of claiming to have yet another 'fail proof'
method to reconstruct our human origins, Ken Wessen wants no
more than to use simulations to investigate the effects normal
day to day decisions can have on the evolutionary lineage of
humans. The decision you may make some day or have already
made to move to another country or to marry this person
instead of that, such decisions can change what our
descendants will look like in the far away future. In his
book, he simulates the evolution of populations by varying
migration, mating strategies, population demographics and
fossilization to investigate the pitfalls of reconstruction of
evolution. The book is divided in two different parts,
depending on the description of two different simulation
programs (downloadable from his website). In the first
simulation, called 'Specialist', the emphasis is on the
problems of reconstruction of relatively simple lineages. For
the mathematicians, he gives a detailed description of the
mathematics used to make the calculations necessary to find
the most recent common ancestors, to determine which fossils
are from surviving lineages and the accuracy of the
reconstructions. For the non-mathematicians, I recommend to
skip these parts and move on to the explanations of the
results, since that is completely comprehensible without the
mathematical background. I should mention here that the
presentation of the results is rather dry. Simulation follows
simulation and points are made in percentage of right and
wrong. Important here is to focus on the message. What the
different mathematical approaches to reconstruction of the
lineages clearly show, is that though not one of the
approaches is completely wrong, none of them is completely
right either. The biggest problem is of course (and I think we
could all guess this) the fossilization rate; the more
fossils, the more accurate the reconstruction will be.
Unfortunately, in real life, fossilization is rare. Therefore,
the results presented by Ken Wessen really force us to be
skeptical about our human lineage. The amount of fossils
placed on the surviving lineage, was consistently over
exaggerated in all simulations. Personally, I think this
reflects on all science publications revealing yet another
missing link in our evolutionary past. Sadly, the truth
apparently is that most of these so called ancestors our not
our 'mothers' or 'fathers', but far more likely our 'second
cousin twice removed'. Still, this is not shocking news to
most of the experts in the field. Another implication made
clear in the book is that the demographics of a population as
well as migrations can also distort the picture of the
reconstructed tree. For example, if we want to find the most
recent European common ancestor, we would not think of looking
for it in let 's say China. However, if the most recent
European common ancestor was a member of a more widely
dispersed population, it could very well be, that due to the
small fossilization rate, the closest fossilized specimen of
this population will be found in China, and not in Europe! And
I think we can all guess what the effect of a population
bottleneck would be on the variation in following generations.
After having disillusioned his readers in the first part of
the book by showing the amount of guess work in reconstructing
lineages, the author moves on to the second simulation, called
'Genie'. With this program, he investigates the influence of
different life decisions in the development of a species.
Factors are for instance: population size, migration, mating
strategies (monogamy, polygyny and polyandry), sex ratio,
mating probability (100% for every female that can mate with
every male), fecundity, infidelity and selection. This part of
the book is somewhat more difficult to follow, because the
figures are less easily interpreted as the trees in part I.
Again, the author starts with describing the mathematics
behind the simulations, so you can either read or skip that
again as previously. In this section, the author simulates
evolution, with the aim to investigate the influence of
above-mentioned factors on the survival of different mutations
in two paternal (Y-chromosome), two maternal (mitochondrial
DNA) and two autosomal genes. For every simulation, the
paternal, maternal and biological common ancestors are
determined, if possible, for three populations, as well as the
common ancestors for all these populations together. Again,
the different parameters can give a great deal of different
outcomes, based on chance (a single simulation can be very
different for the average results of 1000 simulations, and as
we know, evolution only happens once), but also on the
relative timing of events. For instance, immigrants from
another population have a more pronounced effect on the
population they migrate into, when they arrive just after a
population bottleneck. It is also possible that only males
migrate (think of Viking settlement in England) or only
females (for instance abduction of the women after a raid, or
simply marriage, since in most cultures the women go and live
with the husband's family). In summary, the simulations show
the wide variety of outcomes when normal factors in life are
taken into account. This makes it painfully clear, that any
reconstruction of the human lineage will have to take all
these factors into account as well as the times when they
occurred. Therefore, after reading this book, I understand why
the author is so reluctant to include any examples of current
theories in his simulations. In conclusion, Ken Wessen has
made very interesting computer simulations to investigate the
effects of a great number of factors on the evolutionary
development of species. This book is a good read for everybody
with an overly optimistic view of our knowledge of human
history. It is a bit of a shame that the book reads a little
bit like a manual. However, what he describes was, for me at
least, an eye opener and I think his simulations are very
valuable to the field of evolutionary science in general, not
just for human evolution. In fact, human evolution may be the
most problematic, if maybe most appealing, field for which
these simulations can be used.