Saturday, August 19, 2017

A Darwin substitute for Lamarck?

By Mathew Goldstein

Why do animals and plants appear to be well adapted to their environments?  Lamarck had an answer that appears to make sense.  Environmental changes promote behavioral changes which promote corresponding structural adaptations in animals and plants that are transmitted to offspring.  However, Lamarck's hypothesis contradicts the prevailing theory that natural selection acts on random genetic mutations. The post Darwin discovery of genes defeated Lamarck's theory while simultaneously demonstrating the validity of much of Darwin's theory.  Yet there is still some wiggle room here for a superficially Lamarckian, non-random component within the prevailing, random mutation, framework.

Maybe natural selection acts on random mutations to produce outcomes that appear Lamarckian because environmental changes impact particular genes differently.  Particular genes can be stimulated by an environmental change.  Maybe the rate of mutation on stimulated genes increases relative to the rate in genes unaffected by the environmental change.   Because random mutations in that gene are more likely to occur more quickly than would otherwise be the case, the likelihood of a rare beneficial mutation also increases.  Natural selection then favors the rare beneficial mutation in the overall population.

When cells replicate their DNA, the replication by transcription mechanism sometimes stalls. Sometimes, when a stalled replication resumes, a gene sequence is deleted or extra copies of it are made.  A combination of factors could make these copying errors more likely to occur for those particular genes that are actively responding to environmental stresses, so that those particular genes are more likely to show copy number variation.

I read that there is some evidence that "adaptive mutation" of this sort could be occurring in microorganisms.  For example, there is more copy number variation of the copper-resistance gene CUP1 when it is stimulated by environmental copper.  When CUP1 was modified by a team of researchers led by Jonathan Houseley, a specialist in molecular biology and genetics at the Babraham Institute in Cambridge, to react to a non-toxic sugar instead of to copper, an increase in copy number variation result was again seen after the modified CUP1 gene was stimulated by that environmental sugar.  

There is substantial skepticism that adaptive mutation plays a significant role in evolution among biologists.  More and better evidence for stimulated gene localized copy number variation, and a mechanism that translates stimulation of a gene into a higher mutation rate, will be required for this speculative hypothesis to be accepted.  Efforts to prove or disprove adaptive mutation in microorganisms may accelerate as a result of the recent positive CUP1 gene results.  If biologists one day determine that adaptive mutation is true, and probably had some role in humans being one branch on the primate tree, then will more people put aside their religious beliefs and accept that humans are ancestors of microorganisms?

Monday, August 14, 2017

Over there and over here, one difference

By Mathew Goldstein

We collectively make our history.  Human history has its ups and downs.  Our legacy is not particularly good overall, there are many ugly events to relate.  We should not be proud of our history, it is too often shameful.  We need our history, for its pains and glories, and it's ambiguities too, as lessons.  From history we can learn about what not to do, sometimes about what to do, to locate a better future.  From the past we select what history we value when we name our airports, towns, and highways, and who we honor with memorial statues in our public places.  

Having lived my youth in the northeast, I found little difference overall following my move south to the mid-Atlantic past the Mason-Dixon Line.  The Swatztikas on the local train tressle and etched into the public school desks and library cubicles, the German language "Juden" graffiti in black paint on my high school, my immediate neighbor with a pick-up truck whose rear window was covered by a Confederate battle flag, over there.  New co-workers who made a point of telling me that they supported David Duke, the Swatzikas drawn inside a cave, on a motorcyclist's helmet, drawn on the downtown street signs, and building walls, over here.  

However, there is a difference. Here, but not there, the names of Confederate generals were part of the public infrastructure.  Those Confederate generals endorsed, and fought to preserve, commercial kidnapping and enslaving of Africans, many of whom were killed as a result, and whose ancestors live among us today.  The Civil War history was not a part of my life.  My European Jewish ancestors came here during and after WW I, fleeing the anti-semitism that later morphed into the mass murder of Jews who remained in Europe.  Yet this history, both on the Nazi and Confederate sides, kept announcing itself uninvited in odd places and contexts where it did not belong, strangely introduced and repeated by people with crayons, ink, knives, paint, flags, and words.  But with the highway and place names for Confederate war heroes here only.

The people of Charlottesville, like all towns, decide for themselves what history they want to associate themselves with.  They acted reasonably and responsibly when they decided to remove a statue of a Confederate general from their town park.  Among the decisions our local governments face, whether or not that statue resides in a park is not a particularly pressing national concern.  This is primarily a concern for the people living in those towns.

The people with torches and battle flags who thought the public display of this particular statue was so important that they traveled from all over the country to demonstrate for keeping the statue in that park have misdirected priorities.  Adding or removing a statue does not establish, change, or erase the history.   The overreaction against the removal of the statue is evidence that such statues and place names are not innocent and academic placeholders for history.  They are deemed by caucasian, and some Christian, supremacists, such as David Duke and his followers, as representing a positive history that we should emulate, as endorsing traditional attitudes and policies that we should identify ourselves with today.  Instead, more towns and states should follow the positive trend of removing the Confederate war hero statues and place names.  Their essential place is in our history books.  They need not be, and should not be, the statues in our parks or our place names.