Featured Research

from universities, journals, and other organizations

Developmental biologist proposes new theory of early animal evolution that challenges basic assumption of evolution

Date:
October 11, 2012
Source:
New York Medical College
Summary:
A developmental biologist whose life's work has supported the theory of evolution has developed a concept that dramatically alters one of its basic assumptions -- that survival is based on a change's functional advantage if it is to persist.

Developing bodies go on to fold, elongate, and extend appendages, and in some species, generate endoskeletons with repeating elements (e.g., the human hand).
Credit: koszivu / Fotolia

A New York Medical College developmental biologist whose life's work has supported the theory of evolution has developed a concept that dramatically alters one of its basic assumptions -- that survival is based on a change's functional advantage if it is to persist. Stuart A. Newman, Ph.D., professor of cell biology and anatomy, offers an alternative model in proposing that the origination of the structural motifs of animal form were actually predictable and relatively sudden, with abrupt morphological transformations favored during the early period of animal evolution.

Newman's long view of evolution is fully explained in his perspective article, "Physico-Genetic Determinants in the Evolution of Development," which is to be published in the October 12 issue of the journal Science, in a special section called Forces in Development.

Evolution is commonly thought to take place opportunistically, by small steps, with each change persisting, or not, based on its functional advantage. Newman's alternative model is based on recent inferences about the genetics of the single-celled ancestors of the animals and, more surprisingly, the physics of "middle-scale" materials.

Animal bodies and the embryos that generate them exhibit an assortment of recurrent "morphological motifs" which, on the evidence of the fossil record, first appeared more than a half billion years ago. During embryonic development of present-day animals, cells arrange themselves into tissues having non-mixing layers and interior cavities. Embryos contain patterned arrangements of cell types with which they may form segments, exoskeletons and blood vessels. Developing bodies go on to fold, elongate, and extend appendages, and in some species, generate endoskeletons with repeating elements (e.g., the human hand).

These developmental motifs are strikingly similar to the forms assumed by nonliving condensed, chemically active, viscoelastic materials when they are organized by relevant physical forces and effects, although the mechanisms that generate the motifs in living embryos are typically much more complex. Newman proposes that the ancestors of the present-day animals acquired these forms when ancient single-celled organisms came to reside in multicellular clusters and physical processes relevant to matter at this new (for cellular life) spatial scale were immediately mobilized.

The unicellular progenitors are believed to have contained genes of the "developmental-genetic toolkit" with which all present-day animals orchestrate embryonic development, though they used the genes for single-cell functions. It was precisely these genes whose products enabled the ancestral clusters to harness the middle-scale physical effects that produced the characteristic motifs. And since not every ancestral cluster contained the same selection of toolkit genes, different body forms arose in parallel, giving rise to the modern morphologically distinct animal phyla.

Natural selection, acting over the hundreds of millions of years since the occurrence of these origination events led, according to Newman's hypothesis, to more complex developmental processes which have made embryogenesis much less dependent on potentially inconsistent physical determinants, although the "physical" motifs were retained. As Newman describes in his article, this new perspective provides natural interpretations for puzzling aspects of the early evolution of the animals, including the "explosive" rise of complex body forms between 540 and 640 million years ago and the failure to add new motifs since that time. The model also helps us to understand the conserved use of the same set of genes to orchestrate development in all of the morphologically diverse phyla, and the "embryonic hourglass" of comparative developmental biology: the observation that the species of a phylum can have drastically different trajectories of early embryogenesis (e.g., frogs and mice), but still wind up with very similar "body plans."


Story Source:

The above story is based on materials provided by New York Medical College. Note: Materials may be edited for content and length.


Journal Reference:

  1. Stuart A. Newman. Physico-Genetic Determinants in the Evolution of Development. Science, 12 October 2012: 217-219 DOI: 10.1126/science.1222003

Cite This Page:

New York Medical College. "Developmental biologist proposes new theory of early animal evolution that challenges basic assumption of evolution." ScienceDaily. ScienceDaily, 11 October 2012. <www.sciencedaily.com/releases/2012/10/121011141443.htm>.
New York Medical College. (2012, October 11). Developmental biologist proposes new theory of early animal evolution that challenges basic assumption of evolution. ScienceDaily. Retrieved July 25, 2014 from www.sciencedaily.com/releases/2012/10/121011141443.htm
New York Medical College. "Developmental biologist proposes new theory of early animal evolution that challenges basic assumption of evolution." ScienceDaily. www.sciencedaily.com/releases/2012/10/121011141443.htm (accessed July 25, 2014).

Share This




More Plants & Animals News

Friday, July 25, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Boy Attacked by Shark in Florida

Boy Attacked by Shark in Florida

Reuters - US Online Video (July 24, 2014) An 8-year-old boy is bitten in the leg by a shark while vacationing at a Florida beach. Linda So reports. Video provided by Reuters
Powered by NewsLook.com
Goma Cheese Brings Whiff of New Hope to DRC

Goma Cheese Brings Whiff of New Hope to DRC

Reuters - Business Video Online (July 24, 2014) The eastern region of the Democratic Republic of Congo, mainly known for conflict and instability, is an unlikely place for the production of fine cheese. But a farm in the village of Masisi, in North Kivu is slowly transforming perceptions of the area. Known simply as Goma cheese, the Congolese version of Dutch gouda has gained popularity through out the region. Ciara Sutton reports. Video provided by Reuters
Powered by NewsLook.com
Dogs Appear To Become Jealous Of Owners' Attention

Dogs Appear To Become Jealous Of Owners' Attention

Newsy (July 23, 2014) A U.C. San Diego researcher says jealousy isn't just a human trait, and dogs aren't the best at sharing the attention of humans with other dogs. Video provided by Newsy
Powered by NewsLook.com
Professor Creates Site Revealing Where People's Cats Live

Professor Creates Site Revealing Where People's Cats Live

Newsy (July 23, 2014) ​It's called I Know Where Your Cat Lives, and you can keep hitting the "Random Cat" button to find more real cats all over the world. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

    Health News

      Environment News

        Technology News



          Save/Print:
          Share:

          Free Subscriptions


          Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

          Get Social & Mobile


          Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

          Have Feedback?


          Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
          Mobile: iPhone Android Web
          Follow: Facebook Twitter Google+
          Subscribe: RSS Feeds Email Newsletters
          Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins