Freethought & Rationalism Archive

scigirl · 01-18-2002, 10:16 AM

Well, as promised, here is the thread. I will try to include topics that include a wide range of evolution-from humans to bacteria.

1) Evidence of language evolution:
Scientists have known for years that humans have an asymmetric brain structure. One important example is called "Broca's area." This area is critical for speech (we know this from patients who had trauma to that area such as a stroke), and is larger in the left hemisphere.

If we did evolve from primates, we would expect to see asymmetry appear somewhere before hominids appeared, which led to the language advantage. Indeed, Cantalupo and Hopkins at the Yerkes Regional Primate Research Center in Atlanta discovered such proof. They took MRIs (brain scans) of several primates, including chimpanzees, bonobos, and gorillas. They found a similar asymmetry in area 44 of the frontal lobe. Broca's area in humans is in area 44. This asymmetry has existed for at least five million years. Now the scientists are studying this area closer to determine what it does in other primates.

<a href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=117348 39&dopt=Abstract" target="_blank">Asymmetric Broca's area in great apes.</a> Nature 2001 Nov 29;414(6863):505. Cantalupo C, Hopkins WD.

The conclusion of the authors:

Quote:

Whatever the function of area 44 in great apes, our findings indicate that these species show a human-like asymmetry not only in posterior...but also in frontal regions, indicates that the origin of asymmetry in language-related areas of the human brain should be interpreted in evolutionary terms rather than being confined to the human species.

2) Phylogenetic analysis improves:
Anyone who has ever tried to do phylogenetic analysis knows that it can be pretty complicated. Phlogeny is the process of making trees which show evolutionary relationships by comparing gene or protein sequences between species. Creating these trees can be tricky for a number of reasons: First, there are so many possible trees to be analyzed, and second, multiple substitutions in a sequence make it difficult to analyze them. An old mathmatical technique called Bayesian inference is now being employed by scientists to help create phylogenetic trees.

<a href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=117431 92&dopt=Abstract" target="_blank">Bayesian inference of phylogeny and its impact on evolutionary biology.</a>
Science 2001 Dec 14;294(5550):2310-4 Huelsenbeck JP, Ronquist F, Nielsen R, Bollback JP.

Quote:

Instead of searching for the optimal tree, one samples trees according to their posterior probabilities. Once such a sample is available, features that are common among the trees can be discerned.

This technique was employed by researchers to study mammalian evolution:
<a href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=117432 00&dopt=Abstract" target="_blank">Resolution of the early placental mammal radiation using Bayesian phylogenetics.</a>
Science 2001 Dec 14;294(5550):2348-51. Murphy WJ, Eizirik E, O'Brien SJ, Madsen O, Scally M, Douady CJ, Teeling E, Ryder OA, Stanhope MJ, de Jong WW, Springer MS.

The authors determined that placental mammals can be placed in four categories, and they hypothesized that the groups arose when the continents broke up. Before this study, scientists differed about the time that mammals diverged, with the disagreement being 35 million years. This study lends credence to the hypothesis that placental mammals diverged earlier, around 103 million years ago. Many other scientists believe that mammals did not diversify until 65 million years ago, after the dinosaurs went extinct. Despite the controversy, scientists agree that this study does clear up some of the relationships between various mammals.

Quote:

Molecular phylogenetic studies have resolved placental mammals into four major groups, but have not established the full hierarchy of interordinal relationships, including the position of the root. The latter is critical for understanding the early biogeographic history of placentals. We investigated placental phylogeny using Bayesian and maximum-likelihood methods and a 16.4-kilobase molecular data set. Interordinal relationships are almost entirely resolved. The basal split is between Afrotheria and other placentals, at about 103 million years, and may be accounted for by the separation of South America
and Africa in the Cretaceous. Crown-group Eutheria may have their most recent common ancestry in the Southern Hemisphere (Gondwana).

Note: I included some controversial findings, because I think it's important to show anti-evolutionists that scientists are not participating in some conspiracy. Quite the contrary in fact!

Scigirl

[ January 18, 2002: Message edited by: scigirl ]

BLoggins02 · 01-18-2002, 05:27 PM

<img src="graemlins/notworthy.gif" border="0" alt="[Not Worthy]" />

You know, if I could find a lady like yourself, I think I would be happy for the rest of my life.

lpetrich · 01-19-2002, 12:10 AM

One has to purchase access to the full article for $5 with a credit card if one does not subscribe, but I've done so, and I now have a copy of that article. Here are the relationships worked out:

The marsupials selected as outgroups for finding the tree, opossum and kangaroo-like (diprotodontid), cluster together, not surprisingly.

The grouping of eutherian (placental) orders has long been controversial; molecular-evolution research supports some proposed groupings and splits some others. I will be indicating some of these old groupings below. There are 4 major eutherian groups, which have this split order:

[code]
| - Afrotheria
| - | - Xenarthra
| - | - Euarchontoglires
| - Laurasiatheria
</pre>[/quote]

Timing:

Marsupials, others: 173-176 myr (Jurassic), before Laurasia-Gondwana split at 170-160 myr
Afrotherians, others: 100-108 myr (Cretaceous), at South America - Africa split at 120-100 myr
Xenarthrans, others: 88-100 myr
Euarchontoglires - Laurasiathera - 79-88 myr

So there was an adaptive radiation underway while the non-avian dinosaurs were still alive.

Afrotheria, named from the location of their less-dispersed members, contains the old grouping Paenungulata (elephants, sirenians, hyraxes) and the others, (aardvarks, elephant shrews, golden moles, tenrecs). It is well-supported by molecular analyses, although

Of the Paenungulata, hyraxes and sirenians are listed as clustered, though that clustering is only at 60% probability. This does not fit well with the aquatic-phase hypothesis for elephants; either hyraxes had gone through an aquatic phase (unlikely, since they are land animals without outward aquatic adaptations), or elephants and sirenians went into the water separately.

Of the others, aardvarks branched off first, and then the elephant shrews, leaving the golden moles and tenrecs in one group; however, this branching is not 100% probable.

The Xenarthra, native to South America, are also known as Edentata; the armadillos branched off first, leaving the sloths and South American anteaters together.

The remaining two groups the authors grouped together as Boreoeutheria, on account of their origins in the northern continents.

The Euarchontoglires (awkward name; someone may think of a better one) contain two groups, the old group Glires of rodents and lagomorphs and part of the old group Archonta, named Euarchonta.

In Glires, rodents and lagomorphs form separate groups; among the rodents, squirrels diverged first, then guinea pigs, then mice and rats.

In Euarchonta, the tree shrews and flying lemurs form a group alongside the primates.

Going onward to Laurasiatheria, the first group to split off is Eulipotyphla, a renaming of part of the old group Insectivora; the moles split off first, and then the shrews and hedgehogs split.

This is followed by the bats; the diurnal megabats had split off from the mostly-nocturnal microbats.

The remaining group is most of the old group Ferungulata, sometimes renamed Cetferungulata; the first to split off is Artiodactyla (even-toed ungulates), sometimes renamed Cetartiodactyla, with the Perissodactyla (odd-toed ungulates) splitting off next, and the carnivores and pangolins then splitting.

The Cetartiodactyla have this sequence of split-offs: camelids (camel, llama), pigs, ruminants, and then a split between hippopotamuses and cetaceans; the cetaceans are hippos that became even more aquatic.

In the Perissodactyla, the equines split off first, and then the tapirs and rhinos split.

And the carnivores are a coherent group, but with a not-very-surprising split between dogs and cats.

[ January 19, 2002: Message edited by: lpetrich ]

HRG · 01-19-2002, 03:00 AM

Fascinating, as he said raising his eyebrow. Big thanks to scigirl and lpetrich for bringing those news to us!

HRG.

scigirl · 01-19-2002, 05:30 AM

Quote:

Originally posted by BLoggins02:
You know, if I could find a lady like yourself, I think I would be happy for the rest of my life.

Get in line Loggins! My suitors are required to convert at least two fundies before getting my attention (or is it three, I can't remember?)

Scigirl

ksagnostic · 01-19-2002, 06:43 AM

More on great apes and cerebral assymetry can be found here

<a href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=976014 5&dopt=Abstract" target="_blank">http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=976014 5&dopt=Abstract</a>

and

<a href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=942269 3&dopt=Abstract" target="_blank">http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=942269 3&dopt=Abstract</a>

William Hopkins has been publishing alot in this area, and with David Leavins is also looking for functional right handed dominance in intentional communication behaviors by chimpanzees.

Megatron · 01-19-2002, 07:09 AM

Thank you, scigirl!

(and everyone else posting info here as well - didn't mean to leave you guys out.

)

[ January 19, 2002: Message edited by: Archangel ]

scigirl · 02-11-2002, 10:10 AM

February News Flashes:

Science Jan 11, 2002. Vol 295 Page 247.
<a href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=117866 13&dopt=Abstract" target="_blank">Oldest art. From a modern human's brow--or doodling?</a>

Quote:

Archaeologists in South Africa have found what may be the oldest known art, dated at least 40,000 years before the earliest cave paintings in Europe. The artifacts, two chunks of red ochre engraved with geometric crosshatches, were recovered from 77,000-year-old cave deposits. It's unclear what the ancient artist meant the marks to represent. Nevertheless, some researchers argue that the find in Blombos Cave, published online by Science on 10 January (www.scienceexpress.org), strengthens the case that modern human behavior arose much earlier than previously thought and that it took root in Africa long before spreading to Europe.

This article explains that even though scientist believe modern humans arose 130,000 years ago in Africa, there has been a lack of evidence that these humans acted modern, such as tools, art, etc. This artwork, coupled with another discovery in the Journal of Human Evolution that described a cache of elaborately worked bone points in the same area, indicate that this paradox is being resolved. Not all scientists agree with the conclusions, stating,

Quote:

"I have a bit of trouble with the argument that this is now the evidence to displace all claims for the earliest modern behavior elsewhere." At any rate, the findings are exciting, and scientists are now trying to figure out if the location of the art matters more than the date. "Did those anatomically modern people who ended up in a coastal environment do better?" he asks. "This does seem to be the pattern. The search for such patterns, some experts say, might be more important than pinpointing the precise origin of modern behavior. "These authors don't need to make big, bold claims to cinvince us that what they hvae is important, says Conkey. "The intersting question is not so much, 'Is this the earliest?' but 'Why did it happen here?'"

The bone article described above is here:
<a href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=117821 12&dopt=Abstract" target="_blank">An early bone tool industry from the Middle Stone Age at Blombos Cave, South Africa: implications for the origins of modern human behaviour, symbolism and language.</a>

Quote:

Twenty-eight bone tools were recovered in situ from ca. 70 ka year old Middle Stone Age levels at Blombos Cave between 1992 and 2000. These tools are securely provenienced and are the largest collection to come from a single African Middle Stone Age site. Detailed analyses show that tool production methods follow a sequence of deliberate technical choices starting with blank production, the use of various shaping methods and the final finishing of the artefact to produce "awls" and "projectile points". Tool production processes in the Middle Stone Age at Blombos Cave conform to generally accepted descriptions of "formal" techniques of bone tool manufacture. Comparisons with similar bone tools from the Later Stone Age at Blombos Cave, other Cape sites and ethnographic collections show that although shaping methods are different, the planning and execution of bone tool manufacture in the Middle Stone Age is consistent with that in the late Holocene.The bone tool collection from Blombos Cave is remarkable because bone tools are rarely found in African Middle or Later Stone Age sites before ca. 25 ka. Scarcity of early bone tools is cited as one strand of evidence supporting models for nonmodern behaviour linked to a lack of modern technological or cognitive capacity before ca. 50 ka. Bone artefacts are a regular feature in European sites after ca. 40 ka, are closely associated with the arrival of anatomically modern humans and are a key behavioural marker of the Upper Palaeolithic "symbolic explosion" linked to the evolution of modern behaviour.Taken together with recent finds from Klasies River, Katanda and other African Middle Stone Age sites the Blombos Cave evidence for formal bone working, deliberate engraving on ochre, production of finely made bifacial points and sophisticated subsistence strategies is turning the tide in favour of models positing behavioural modernity in Africa at a time far earlier than previously accepted.

scigirl

scigirl · 02-11-2002, 10:23 AM

Evolution News Flash:

Science Jan 11,2002. Vol 295.

<a href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=117866 41&dopt=Abstract" target="_blank">Sex-biased hatching order and adaptive population divergence in a passerine bird.</a>

Quote:

Most species of birds can lay only one egg per day until a clutch is complete, and the order in which eggs are laid often has strong and sex-specific effects on offspring growth and survival. In two recently established populations of the house finch (Carpodacus mexicanus) in Montana and Alabama, breeding females simultaneously adjusted the sex and growth of offspring in relation to their position in the laying order, thereby reducing the mortality of sons and daughters by 10 to 20% in both environments. We show experimentally that the reduction in mortality is produced by persistent and sex-specific maternal effects on the growth and morphology of offspring. These strong parental effects may have facilitated the rapid adaptive divergence among populations of house finches.

This research was carried out in Montana, at that "other" school (UM, Missoula).

The finches have adapted to their new environments by, in part, controlling the sex of their eggs. The birds spread from New York to Alabama, and from California to Montana, at around the same time in the 1930's. In Alabama, the males have a faster growth rate and have longer tails and wider bills. In Montana, it's reversed--females have those traits. The researchers found that the differences correlated to egg-laying patterns. Alabama finches lay male eggs first, and in Montana, the female eggs are laid first. And with these birds, the egg laid first has the growth advantage.

The news summary in the same issue has this to say(page 249):

Quote:

"The time scale of decades [not centuries] is really enough for animals to evolve, notes David Reznick, an evolutionary biologist at the University of California, Riverside."

scigirl

Valentine Pontifex · 02-11-2002, 05:05 PM

Quote:

Originally posted by scigirl:
Well, as promised, here is the thread. I will try to include topics that include a wide range of evolution-from humans to bacteria.

Evolution from humans to bacteria.

Well that explains the YECs. :-)

(I do see the hyphen, but I just could not help myself. So forgive me if I act like a YEC and concentrate on the words and not the meaning.)

[ February 11, 2002: Message edited by: LordValentine ]

01-19-2002, 12:10 AM	#3
lpetrich Contributor Join Date: Jul 2000 Location: Lebanon, OR, USA Posts: 16,829	One has to purchase access to the full article for $5 with a credit card if one does not subscribe, but I've done so, and I now have a copy of that article. Here are the relationships worked out: The marsupials selected as outgroups for finding the tree, opossum and kangaroo-like (diprotodontid), cluster together, not surprisingly. The grouping of eutherian (placental) orders has long been controversial; molecular-evolution research supports some proposed groupings and splits some others. I will be indicating some of these old groupings below. There are 4 major eutherian groups, which have this split order: [code] \| - Afrotheria \| - \| - Xenarthra \| - \| - Euarchontoglires \| - Laurasiatheria </pre>[/quote] Timing: Marsupials, others: 173-176 myr (Jurassic), before Laurasia-Gondwana split at 170-160 myr Afrotherians, others: 100-108 myr (Cretaceous), at South America - Africa split at 120-100 myr Xenarthrans, others: 88-100 myr Euarchontoglires - Laurasiathera - 79-88 myr So there was an adaptive radiation underway while the non-avian dinosaurs were still alive. Afrotheria, named from the location of their less-dispersed members, contains the old grouping Paenungulata (elephants, sirenians, hyraxes) and the others, (aardvarks, elephant shrews, golden moles, tenrecs). It is well-supported by molecular analyses, although Of the Paenungulata, hyraxes and sirenians are listed as clustered, though that clustering is only at 60% probability. This does not fit well with the aquatic-phase hypothesis for elephants; either hyraxes had gone through an aquatic phase (unlikely, since they are land animals without outward aquatic adaptations), or elephants and sirenians went into the water separately. Of the others, aardvarks branched off first, and then the elephant shrews, leaving the golden moles and tenrecs in one group; however, this branching is not 100% probable. The Xenarthra, native to South America, are also known as Edentata; the armadillos branched off first, leaving the sloths and South American anteaters together. The remaining two groups the authors grouped together as Boreoeutheria, on account of their origins in the northern continents. The Euarchontoglires (awkward name; someone may think of a better one) contain two groups, the old group Glires of rodents and lagomorphs and part of the old group Archonta, named Euarchonta. In Glires, rodents and lagomorphs form separate groups; among the rodents, squirrels diverged first, then guinea pigs, then mice and rats. In Euarchonta, the tree shrews and flying lemurs form a group alongside the primates. Going onward to Laurasiatheria, the first group to split off is Eulipotyphla, a renaming of part of the old group Insectivora; the moles split off first, and then the shrews and hedgehogs split. This is followed by the bats; the diurnal megabats had split off from the mostly-nocturnal microbats. The remaining group is most of the old group Ferungulata, sometimes renamed Cetferungulata; the first to split off is Artiodactyla (even-toed ungulates), sometimes renamed Cetartiodactyla, with the Perissodactyla (odd-toed ungulates) splitting off next, and the carnivores and pangolins then splitting. The Cetartiodactyla have this sequence of split-offs: camelids (camel, llama), pigs, ruminants, and then a split between hippopotamuses and cetaceans; the cetaceans are hippos that became even more aquatic. In the Perissodactyla, the equines split off first, and then the tapirs and rhinos split. And the carnivores are a coherent group, but with a not-very-surprising split between dogs and cats. [ January 19, 2002: Message edited by: lpetrich ]</p>

01-19-2002, 07:09 AM	#7
Megatron Veteran Member Join Date: Oct 2000 Location: New York Posts: 5,441	Thank you, scigirl! (and everyone else posting info here as well - didn't mean to leave you guys out. ) [ January 19, 2002: Message edited by: Archangel ]</p>

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01-18-2002, 05:27 PM	#2
BLoggins02 Regular Member Join Date: Dec 2001 Location: College Station, TX Posts: 254	<img src="graemlins/notworthy.gif" border="0" alt="[Not Worthy]" /> You know, if I could find a lady like yourself, I think I would be happy for the rest of my life.

01-19-2002, 03:00 AM	#4
HRG Veteran Member Join Date: May 2001 Location: Vienna, Austria Posts: 2,406	Fascinating, as he said raising his eyebrow. Big thanks to scigirl and lpetrich for bringing those news to us! HRG.

01-19-2002, 06:43 AM	#6
ksagnostic Veteran Member Join Date: Jun 2000 Location: Wichita, KS, USA Posts: 2,514	More on great apes and cerebral assymetry can be found here <a href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=976014 5&dopt=Abstract" target="_blank">http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=976014 5&dopt=Abstract</a> and <a href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=942269 3&dopt=Abstract" target="_blank">http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=942269 3&dopt=Abstract</a> William Hopkins has been publishing alot in this area, and with David Leavins is also looking for functional right handed dominance in intentional communication behaviors by chimpanzees.

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