Monday, June 20, 2005

Pigliucci on Expanding the Synthesis

Nature recently ran this interesting book review by Massimo Pigliucci. The book under review is Evolution in Four Dimensions: Genetic, Epigenetic, Behavioral, and Symbolic Variation in the History of Life by Eva Jablonka and Marion J. Lamb. Pigliucci writes:

There have been rumblings for some time to the effect that the neo-darwinian synthesis of the early twentieth century is incomplete and due for a major revision. In the past decade, several authors have written books to articulate this feeling and to begin the move towards a second synthesis. David Rollo, in his book Phenotypes (Kluwer, 1994), was among the first to attempt to bring the focus back to the problems posed by phenotypic evolution. In Phenotypic Evolution (Sinauer, 1998), Carl Schlichting and I framed the debate in terms of the integration of development, environment and genetics by articulating the concept of “developmental reaction norms”. Stephen Jay Gould then produced an overly long (and at times acrimonious) sketch of the new synthesis in The Structure of Evolutionary Theory (Harvard University Press, 2002). Finally, Mary-Jane West-Eberhard, in Developmental Plasticity and Evolution (Oxford University Press, 2003), greatly expanded on my book and the one by Rollo, producing the most comprehensive alternative account of evolutionary theory yet. Evolution in Four Dimensions by Eva Jablonka and Marion Lamb is the most recent addition to this genre, and contributes yet another valuable perspective to the discussion.

Jablonka and Lamb, as described by Pigliucci, argue that there are really four different sources of inheritance. He writes:

The authors argue that there is more to heredity than genes; that some hereditary variations are non-random in origin; that some acquired information is inherited; and that evolutionary change can result from 'instruction' as well as selection. This may sound rather revolutionary, even preposterously close to lamarckism. But Jablonka and Lamb build on evidence from standard research in evolutionary and molecular biology, and their case should be examined on its merits, rather than being dismissed by a knee-jerk reaction.

Consider the charge of lamarckism. Jablonka and Lamb happily embrace the term, but with one important qualification. As they correctly point out, there are at least two very distinct meanings of the word. Most biologists associate lamarckism with the idea of direct adaptive feedback from the soma to the germ line. That version of lamarckism is dead, killed off by our understanding of molecular biology, and nobody is attempting to revive it.

The second meaning is actually closer to the core of Lamarck's ideas, which are rarely, if ever, read by modern biologists. The suggestion is that some heritable, adaptive changes come not from natural selection, but from the action of evolved internal systems that generate non-random 'guesses' in response to environmental challenges. Examples are not hard to find, contrary to the assumed wisdom of standard neo-darwinism. Consider the existence of 'hotspots' that make mutations in certain regions of the genome much more likely than in others. Or the impressive ability of some bacteria to increase the mutation rate of a specific gene involved in the metabolism of a given amino acid when that amino acid becomes scarce in the environment.

The whole review is worth reading. And the book itself has now been added to the queue.

I have commented before at this blog that the problem facing evolutionary biologists is never “How could bit of anatomy X possibly have evolved naturally?” Rather, the question is “Of the many possible mechanisms by which this system might have evolved, which is the correct one?” It seems that scientists are constantly discovering new mechanisms for explaining evolution, even to the point of unseating natural selection as the sole crafter of adaptive change (if Jablonka and Lamb are correct). This is enormously exciting stuff.

Of course, any talk of fiddling with the neo-Darwinian synthesis tends to make the hearts of creationists go pitter pat. They know that any suggestion that the nineteen fifties version of evolution may have been incomplete can be spun into a statement that evolution is dying. They will conveniently ignore the fact that the discoveries that are pursuading scientists of the incompleteness of the original synthesis are all in the direction of making evolutionary change easier, not harder, to explain. They won't mention that evolutionary theory is strengthened by the developments Pigliucci describes.

The crafters of the original synthesis restricted their explanatory options unnecessarily. The reality is that biologists are faced with an embarrassment of riches in trying to explain evolutionary change.


At 2:46 PM, Blogger MichaelBains said...

I really don't know how I've never read this blog before. This stuff is interesting man! LOL!

Thank you.

At 4:30 PM, Blogger Jason said...

And thank you for the kind words. Glad you like the blog.

At 5:23 PM, Blogger Paul said...

Just a quick word about the bacteria (it is my thing :)). The trait that is being described ("adaptive mutation" is one common descriptor) has been quite controversial, and I'm not sure that citing it as established fact is warranted. Bacteria have well understood mechanisms for changing their DNA repair mechanisms when stressed (hypermutator phenotypes) that allow for reduced stringency in genome structure, and thus allow potentially beneficial mutations to arise. It was proposed that this was even more directed, and that directed or adaptive mutation could take place, governed by transcription. As I said, there has been much debate on the topic (i'm not specifically in that field of microbiology), and to my knowledge, no firm resolution. Interesting topic, and one worth much more study.

At 6:03 PM, Anonymous penis enlargement pill said...

penis enlargement pill
buy viagra
Buy Viagra
Generic Viagra




mp3 players
buy mp3 players
cheap mp3 players
wholesale mp3 players
portable mp3 players


purchase viagra
buy Cialis
buy Cialis

At 8:38 AM, Anonymous penis pill said...

A real enlightening blog. Don't stop now. If you happen to be looking for penis pill, I'm sure you'd be interested in penis pill

At 6:28 AM, Blogger Jorolat said...

Do you have the title of the book review please? I don't have a subsciption to Nature and can't access the review via your link.

Very interesting stuff though!

John Latter
Evolution Research Blog

At 12:55 AM, Anonymous viagra said...

Viagra is definitely a better from of erectile dysfunction treatment than gene therapy, a mode of anti-impotency treatment that has yielded successful results in treating erectile dysfunction in men. But before getting hold of viagra, it would be better for you to go through the website and procure the necessary details on the medicine.

At 3:56 AM, Blogger kevin said...

Your search for weight loss drugs as well as medicines to treat depression and anxiety end completely as you come in touch with the website and particularly if you are looking forward to avail of fundamental tidbits on erectile dysfunction drugs such as Viagra then is the ultimate destination for you. After getting hold of important Viagra details from this website such as Viagra mechanism, viagra safety information et al, you can easily procure a Viagra prescription from the doctor and kick start your erectile dysfunction treatment.

At 12:17 AM, Blogger Powell Livia said...

Erectile dysfunction (ED) affects the lives of many middle-aged men and their partners to one extent or another. The term erectile dysfunction, previously known as impotence, covers a wide range of disorders, but usually refers to the inability of a man to achieve or maintain an erection sufficient enough to fulfill his own sexual needs or those of his partner.

At 1:04 AM, Blogger sandra said...

Generic Viagra has helped millions of men with erectile dysfunction achieve improved erections. This pill is shown to help men get and keep an erection for successful intercourse.

At 11:56 PM, Blogger SundayRose said...

Propecia is a steroid reductase inhibitor, works by reducing the amount of the hormone dihydrotestosterone in the body. This may block certain types of hair loss in men.

At 12:40 AM, Blogger reggiewhite said...

Generic Cialis works by helping the blood vessels in your penis to relax, allowing the flow of blood into your penis. The result of this is improved erectile function.

At 1:56 AM, Blogger johnnysmith said...

Generic Cialis is consumed orally and has quickly become one of the most prescribed medications. Generic Levitra has been clinically proven to improve erectile function, even in men who had other health factors, like high cholesterol, high blood pressure, or diabetes

At 1:24 AM, Anonymous Anonymous said...

generic viagra
generic viagra
online pharmacy
buy viagra
buy viagra online
generic viagra
generic cialis
generic viagra
buy cialis

At 6:11 PM, Anonymous Penis Enlargement Pills said... is an all-natural Penis Enlargement, safe, and guaranteed alternative to painful and dangerous Penis enlargement methods such as surgery, straps, or rings.
penis enlargement pills or male enhancement pills will immediately boost your performance, improve your orgasms, and increase the size of your penis within just a few weeks!


At 11:09 PM, Anonymous buy generic viagra said...

Nice blog.I really like your blog.Keep posting and sharing like these.

At 4:03 AM, Anonymous viagra online said...

Thanks for sharing your ideas. I was desperately waiting for such posts. I really appreciate your efforts and I will be waiting for your further write ups thanks once again.

At 1:13 AM, Anonymous mens health said...

hi there,
nice information provided.
keep posting kind of blogs in the future.

At 3:58 AM, Anonymous Penis Enlargement Pills said...

You made some good points there. I did a search on the topic and found most people will agree with your blog.

At 2:18 AM, Anonymous xanax without a prescription said...

I really admire this, I mean it really looks interesting! Very nice write up. Anyways, its a Great post.

At 7:07 AM, Anonymous diazepam without prescription said...

Wow! It's awesome blog post here. really very interesting for reading.Like those pictures.. I enjoyed it.

At 12:29 AM, Anonymous viagra dosage recommended said...

Wow, nice post,there are many person searching about that now they will find enough resources by your post.Thank you for sharing to us.Please one more post about that..

At 1:25 AM, Anonymous By Viagra Online said...

Wow very nice post.....!

At 1:23 AM, Anonymous Business Logo Design said...

This is one of the most incredible blogs I have read in a very long time. Your blog is great for anyone who wants to understand this subject more. Great stuff.

At 1:14 AM, Anonymous Extenze Pills said...

Thank you for sharing to us. Please one more post about that.

At 2:18 AM, Anonymous Rahul saini said...

You made some good points there. I did a search on the topic and found most people will agree with your blog.


Post a Comment

<< Home