Forward and Backward
Last Friday’s Star-Ledger noted the death, at age 111, of Ernest
Pusey, one of the very few remaining veterans of World War I.
Less than two weeks before he died in Florida, Governor Jeb
Bush had presented Pusey with a World War I Victory Medal.
Am I related to Mr. Pusey? My mother’s maiden name was
Pusey. She was born just a couple of years after Ernest. Not
only was her father’s name Pusey but her mother’s maiden name
was also Pusey. My grandparents were cousins. Apparently,
marrying a cousin was not that uncommon back in the 1800s.
Today, the dangers of marrying within a family are well known.
If there’s a defective gene in the family and both parents carry
the gene, it’s likely their children will also inherit that gene. If
only one parent carries the culprit gene, this possibility is vastly
reduced or eliminated. The “good” gene from the other parent
supplies the “good” protein that prevents any associated disease
or deformity. My mother was one of four sisters. All four died
at age 69 and I’ve often wondered whether there was a “bad”
gene shared by their closely related parents, my grandparents.
Some time ago, I read about a family in which some siblings
walked on all fours. There was a claim that this was “reverse
evolution” in which an ancient gene was activated taking the
siblings back millions of years ago when our ancestors walked
on all four limbs. Last week I watched PBS’s Nova program
about this family, which lives in a remote section of Turkey.
Sure enough, the father and mother are close cousins. They had
19 children, 12 of whom are perfectly normal.
Six children, however, walked on all fours; five are still living,
ranging in age from 18 to 34. A seventh sibling walks on two
legs but has a very unsteady gait resembling that of a drunken
man. The program was disturbing; one look into the eyes of
these unusual individuals and you knew that they suffer from
more than their strange mode of locomotion. They walk on the
palms of their hands, not a throwback to our early ancestors.
Three million years ago, our human ancestors walked on two feet
but also maintained a wrist bone structure found in our primate
cousins such as the chimpanzee. Our great ape relatives can
walk on their two feet or on all fours. In the latter case, they
walk on their knuckles. The wrists of apes and our 3-million-
year-old ancestors such as Lucy, mentioned here recently, are
and were not flexible. Our wrists, on the other hand, are quite
flexible and permit the Turkish siblings to walk on their palms,
an argument against the “reverse” evolution claim.
Indeed, one British researcher, Nicholas Humphrey, says that
calling the siblings a case of backward evolution is insulting to
the family and scientifically irresponsible. In the remote village,
neighbors tend to shun the family and children taunt the five
siblings. Apparently, the family’s Islamic faith and the
remoteness of their village have heretofore led the family to
accept their fate without attempting to seek help. With the public
exposure, however, things have changed.
The family has allowed MRI brain scans and analyses of blood
samples to find the defective genes. The brain scans reveal a big
problem – the sibling’s cerebellums are significantly smaller and
deformed compared to those of normal individuals. The
cerebellum is involved in balance and coordination of limb
movement. The affected siblings also have difficulties with
language. Studies are still in progress to pin down the exact gene
or genes responsible for the strange behavior.
Remarkably, it seems that the father and mother, accepting their
fate, did not or could not seek out expert medical attention.
Nobody had thought to try to correct the four-limb problem by
even having the siblings try using a simple walker. Now,
however, a Turkish doctor expert in physical rehabilitation has
the siblings working with walkers and parallel bars to try to
achieve a bipedal mode of walking. The doctor held out hope
that the four sisters would eventually walk more or less normally
but did not expect the brother, who has been walking this way for
28 years, to ever be able to switch. However, the most touching
part of the Nova program came near the end when the brother
appeared walking, albeit very shakily, upright on two feet.
Normally, a baby who showed no signs of walking on two feet
would be referred for medical attention and physical therapy and
would soon be walking on two feet. The idea of reverse
evolution would not arise. It may not qualify as evolution but the
Nova program briefly showed a dog in Oklahoma City named
Faith. Faith was born without her two front legs. Yet she walks
around the city as upright as you please on her two hind feet. I
should have her posture!
Now let’s consider a case of “forward” evolution that in a sense
is a case of reversing an evolutionary trend in order to promote
survival. Brian Trumbore called my attention to an article by
Lewis Smith in the November 17 New York Times. The Times
article dealt with work by Jonathon Losos and coworkers
published in Science on the same date. Without Brian’s alert, I
would have ignored the Science article, titled “Rapid Temporal
Reversal in Predator-Driven Natural Selection”. The research,
on lizards, offered the researchers from Washington University
in St. Louis and the University of California, Davis a chance to
spend two Mays and a November in the Bahamas – not bad.
This tale involves the brown arole lizard, which spends roughly
40% of its time on the ground and the rest up in trees. Over time,
the brown lizard has developed long legs that allow it to run
faster to get away from predators. The northern curly-tailed
lizard is the bad guy; Curly tends to eat Brownie. However,
Curly sticks to the ground. In the Bahamas there are lots of
small islands and on some of them only the brown lizards are
present. So, what would you do if you were Brownie and
someone dumped a bunch of the curly-tails on your island?
Well, I don’t know about you but I would take to the trees pretty
quickly since Curly sticks to the ground.
The researchers found 12 small islands in the Bahamas that only
had the Brownies on them. On six of the islands they introduced
substantial numbers of the curly-tails, leaving the other six
islands untouched as controls. At the beginning and then at six-
month intervals they made a careful census of the brownies,
measuring them and noting their locations. As I would have
done, the Brownies started climbing and after 6 months spent
roughly 10% of the time on the ground, not the normal 40%.
After a year, the time on the ground was down to nearly 5%.
In the first six months the Brownies fared better with longer legs,
allowing them to run faster to avoid the Curlies when first
introduced. However, in the next six months, as the Brownies
took to the trees, it became more advantageous to develop shorter
hind legs to better navigate on the tree limbs and branches. In
other Caribbean islands, it has already been shown that, when the
lizards spend more time in the trees, their hind legs get shorter.
Hence the “reverse” evolution in this case where introducing a
predator, spurred a rapid change in habitat and a reversal of an
existing trend to develop longer legs. Evolution can happen
quickly and not just in the world of drug resistant bacteria and
Incidentally, my 79th birthday is coming up in a few weeks.
Does that mean I owe those extra ten years to my father’s good
genes? He lived into his 90s. I’ll never know.
Allen F. Bortrum