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Topic: Most recent common ancestor

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	Common ancestor - EvoWiki
		Identifying common ancestors is one of the tasks you have to do when systematically ordering known species.
		Usually it is these recent common ancestors that biologists/paleontologists are concerned with, and the most recent link between later species would be the last common ancestor (LCA) while the LCA of all contemporary life on Earth is known as the Last Universal Common Ancestor (LUCA).
		A fossil of the common ancestor or a related form is a transitional fossil.
	wiki.cotch.net /index.php/Common_ancestor (281 words)

	Common descent - Wikipedia, the free encyclopedia
		The most recent common ancestor is the most recent population or species which is an ancestor of all of the species being referenced, whether that be polar bears and sun bears or woolly mammoths and African elephants or even all four of those species which ancestor would most likely be one of the earliest mammal.
		The broadest form of common descent is universal common descent, which is the theory that all life on earth originated from one the same common ancestor billions of years ago.
		Common vegetables such as cabbage, kale, broccoli, cauliflower, kohlrabi and Brussels sprouts are all decedents of the wild mustard plant.
	en.wikipedia.org /wiki/Common_descent (802 words)

	Common ancestors of all humans
		Common Ancestor of all living humans - There are trillions of these, stretching from the origin of DNA-based life 4 to 3.5 billion years ago to a lot more recently - perhaps even within historical times, as we shall see.
		Most Recent Common Ancestor of all living humans - This is a human, perhaps even within historical times, as we shall see.
		The MRCA is a "statistical artefact", and is unlikely to be significant (or at all noticeable) in archaeology.
	humphrysfamilytree.com /ca.html (1773 words)

	Unexplained Mysteries :: 'Most recent common ancestor' of all living humans
		In this week's issue of Nature, a Yale mathematician presents models showing that the most recent person who was a direct ancestor of all humans currently alive may have lived just a few thousand years ago.
		Those precise mathematical results showed that in a world obeying the simplified assumptions, the most recent common ancestor would have lived less than 1,000 years ago.
		He also introduced the "identical ancestors point," the most recent time -- less than 2,000 years ago in the simplified model -- when each person was an ancestor to all or ancestor to none of the people alive today.
	www.unexplained-mysteries.com /viewnews.php?id=23487 (252 words)

	UCMP Glossary: Phylogenetics
		The points at which lineages split represent ancestor taxa to the descendant taxa appearing at the terminal points of the cladogram.
		Derived characters are those acquired by the most recent common ancestor of the taxa under consideration.
		Fairly common in certain land plant clades; reticulation is thought to be rare among metazoans.
	www.ucmp.berkeley.edu /glossary/gloss1phylo.html (1380 words)

	Most recent common ancestor - Wikipedia, the free encyclopedia
		The most recent common ancestor (MRCA) of any set of organisms is the most recent individual which is an ancestor of all of them, except itself.
		The MRCA of everyone alive today could have co-existed with a large human population, most of whom either have no living descendants today or else are ancestors of almost everyone alive today.
		An explanation of this result is that, while humanity's MRCA was indeed a Paleolithic individual up to Early Modern times, the European explorers of the 16th and 17th centuries would have fathered enough offspring so that some "mainland" ancestry by today pervades even remote habitats.
	en.wikipedia.org /wiki/Most_recent_common_ancestor (1006 words)

	NOVA Online \| Neanderthals on Trial \| Tracing Ancestry with MtDNA
		Let's get back to "Eve." The ancestor referred to in the 1987 Nature article can be more precisely stated as "the most recent common ancestor through matrilineal descent of all humans living today." In other words, she is the most recent person from whom everyone now living on Earth has inherited his or her mtDNA.
		Furthermore, her status as the most recent common ancestor doesn't mean that she and her contemporaries were any different from their ancestors.
		Perhaps the most valuable finding regarding the "most recent common ancestor" is that she probably lived in Africa -- a finding that supports the most popular theories about the worldwide spread of hominids.
	www.pbs.org /wgbh/nova/neanderthals/mtdna.html (1816 words)

	Paleorama.com
		Mitochondrial Eve is the most recent common matrilineal (female-lineage) ancestor, not the most recent common ancestor (MRCA) of all humans.
		The MRCA's offspring have led to all living humans, but Mitochondrial Eve must be traced only through female lineage, so she is estimated to have lived much longer ago than the MRCA.
		According to the most common interpretation of the mitochondrial DNA data, the titles belong to the same hypothetical woman.
	www.paleorama.com /more/eve.html (1202 words)

	Using DNA to find ancestors
		Most of you are researching your Wade ancestors -- trying to document at least one more generation back in the chain or trying to find the descendants of a particular person.
		The trick is to reduce the uncertainty in the determination of that MRCA until you have identified the individual who is the father of both of your family lines.
		If two men are 8th generation descendants from a common ancestor (they had a common ancestor about 140 years ago), there are 7 births down each line to the men tested.
	home.cfl.rr.com /wade3/usedna.htm (1052 words)

	Most Recent Common Ancestors: Interesting Thing of the Day
		By examining hundreds of samples from all over the world, researchers have determined how recently a woman could have lived who is a direct ancestor of everyone tested, which by extension implies nearly everyone in the world.
		Using the same sort of “molecular clock” that indicated how far back a common female ancestor was, geneticists have determined that the most recent male ancestor of everyone currently alive—called “Y-chromosomal Adam”—lived about 60,000 years ago (again, give or take a few tens of thousands of years).
		See Common ancestors of all humans as well as separate discussions on Common ancestors of all humans (using genetics) and Common ancestors of all humans (using mathematical models).
	itotd.com /articles/226/most-recent-common-ancestors (1467 words)

	Most Recent Common Ancestor
		In other words, the Most Recent Common Ancestor is not a person -- he is a graph, or a range of probabilities.
		Mutations that alter a person's phsyical appearance or cause a genetic disease tend to be either very common (if the mutation is helpful) or very rare (because everyone with the mutation dies young).
		The Most Recent Common Ancestor analysis will be different depending on the estimated mutation rate, as well as the mathematical model that is used to crunch the numbers.
	www.moonzstuff.com /cheekdna-mrca.html (1415 words)

	Cladistics
		Cladistics is currently the most popular paradigm of phylogenetic classification in biological taxonomy.
		Most of them were 'pet characters' of one or another authority, and the 'minor' characters that contradicted them were regarded as homoplasies or simply not considered.
		So we have a situation where apparent "ancestors" (well, the grand-uncles rather than the grand-fathers, because cladistics is all about the descendents of the common ancestor, never the common ancestor at the base of the node) appear after their "descendents"
	www.kheper.net /evolution/systematics/cladistics.htm (1704 words)

	Common ancestors of all humans (using mathematical models)
		Modelling the recent common ancestry of all living humans, Douglas L. Rohde, Steve Olson and Joseph T. Chang, Nature 431 (7008), 562-6, (September 30, 2004), "Letters to Nature".
		With random mating, the MRCA would be c.1200 AD Many mathematical models are of 1-parent genealogies - which is basically like modelling the female-female or male-male CAs.
		Chang says this medieval MRCA is implausible (though as my Royal Descents page illustrates, it is not that implausible at all) and notes that one problem with applying the model to humans is random mating.
	humphrysfamilytree.com /ca.math.html (1599 words)

	Dictionary
		For example, the most recent common ancestor of all modern birds and all its descendants is the crown clade Neornithes.
		The long neck of the giraffe is apomorphic; the short neck of its ancestor is plesiomorphic; a character present throughout a taxon because it is present in an outgroup of the taxon --plesiomorphy n.
		all descendants of the most recent common ancestor of turtles, lepidosaurs (tuataras and squamates), and archosaurs (crocodilians and birds).
	www.dinosauria.com /dml/diction.htm (3740 words)

	Ancestor of HIV-1 pandemic strains first occurred about 1930, Los Alamos researchers say
		HIV is considered to be the result of chimpanzee-to-human transmission since it is most closely related to a group of simian immunodeficiency viruses (SIVs) found in chimpanzees that have a geographic range in West Equatorial Africa.
		Previous efforts to date the most recent common ancestor of the M group have yielded less accurate results because they were based on fewer HIV-1 sequences and used less refined evolutionary models.
		In the recent study, physicists Bhattachurya and James Theiler produced a computer code and provided a statistical analysis; the Laboratory's Nirvana supercomputer was used for generating the computationally intensive phylogenetic trees, and a maximum likelihood method was developed for correlating distances between branches in a genetic tree to the passage of time.
	www.lanl.gov /worldview/news/releases/archive/00-078.shtml (765 words)

	[No title]
		For example, it is more parsimonious to infer that a vertebral column evolved only once in a common ancestor of all living vertebrates than to infer that it evolved multiple times, once for fish, once for amphibians, etc. The first option requires fewer evolutionary changes.
		nucleic acids, metabolic pathways), it is most parsimonious to conclude that all of life as we know it (currently and historically) shares a common ancestor.
		Therefore, we know that this body shape must have arisen on the branch between the common ancestor of cetaceans and artiodactyls and the MRCA of all known cetaceans.
	biology.unm.edu /ccouncil/Biology_203/Summaries/Phylogeny.htm (1371 words)

	PhyloCode Article 11 (Site not responding. Last check: 2007-09-17)
		There may be evidence suggesting that another species that was included in the analysis shares a recent common ancestor with the type.
		If a name is defined through a branch-based definition with more than one internal specifier, and one internal specifier is later found to share a more recent common ancestor with the external specifier than with the other internal specifier, the definition does not apply to any clade.
		Because it is not always possible to be faithful to all traditions simultaneously, which tradition is most important to maintain is left to the discretion of the author of the converted name.
	www.ohiou.edu /phylocode/art11.html (2179 words)

	Biology News: Human populations are tightly interwoven
		Besides dating our most recent common ancestor, Rohde's team also calculates that in 5,400 BC everyone alive was either an ancestor of all of humanity, or of nobody alive today.
		The researchers call this the 'identical ancestors' point: the time before which all the family trees of people today are composed of exactly the same individuals.
		At the identical ancestors point, then, our ancestors came from every corner of the globe, although those from far afield are unlikely to have made a significant contribution to our genetic make-up.
	www.bioedonline.org /news/news.cfm?art=1261 (786 words)

	What, if anything, is a Mitochondrial Eve?
		She is the most-recent common ancestor of all humans alive on Earth today with respect to matrilineal descent.
		The title at that time was held by a distant ancestor of hers (and of the many humans who were her contemporaries).
		The older ME is still the common ancestor of all humans alive today on Earth with respect to matrilineal descent, but she is not the most-recent...
	www.talkorigins.org /faqs/homs/mitoeve.html (1779 words)

	Understanding DNA Results
		For example, if all 25/25 markers match, there is a 50% probability that the most recent common ancestor was no longer than 7 generations, and a 90% probability that the most recent common ancestor was within the last 98.8 generations.
		A perfect match on the 12 marker test 12/12 would show that there was a 50% probability that the most recent common ancestor was within 14.5 generations and a 90% probability that the most recent common ancestor was within 48 generations.
		"The common practice in paternity testing is that a difference at one or two out of 6-15 STR loci commonly analyzed is attributed to mutation rather than non-paternity, whereas differences at more than two loci are interpreted as non-biological paternity."
	www.angelfire.com /nb/stewartdna/Understanding_DNA_Results.htm (1299 words)

	Scientists Recreate Genome of Ancient Human Ancestor
		Scientists have recreated part of the genetic code of an extinct, shrewlike creature that is thought to have been the most recent common ancestor of most placental mammals, including humans.
		The results allowed the scientists to reconstruct a DNA sequence common to each species, including their common ancestor, thought to be the mother of most placental mammals.
		Scientists recreated part of the genome of a later species, known simply as the "boreoeutherian ancestor," which is thought to be the most recent common ancestor of all placental mammals.
	news.nationalgeographic.com /news/2005/01/0125_050125_genome.html (931 words)

	R. Thomson et al., Recent common ancestry of human Y chromosomes
		Mitochondrial DNA originally was used for this purpose, because the high mutation rate of mitochondrial DNA produced numerous polymorphisms and the absence of recombination facilitated their interpretation.
		The authors used these data to study the ancestral genealogy of human Y chromosomes, with a particular focus on estimating the expected time to the most recent common ancestor and the expected ages of certain mutations with interesting geographic distributions.
		The geographic variation distribution was found similar to that obtained for other gene loci, but the expected time to the most recent common ancestor is remarkably short, on the order of 50,000 years.
	www.sscnet.ucla.edu /comm/steen/cogweb/Abstracts/Thomson_00.html (550 words)

	Random descent networks
		Previous study of the time to a common ancestor of all present-day individuals has focused on models in which each individual has just one parent in the previous generation.
		As Chang says in the discussion, "[t]he descendants of a common ancestor need not share any particular DNA from that ancestor, and it is even possible that none of the descendants has inherited any DNA from the ancestor.
		Our ability to detect this common ancestor may be affected by these genetic circumstances, but the fact that we have a common grandfather would remain.
	www.ldc.upenn.edu /myl/descent/Random_descent_networks.html (1612 words)

	Estimating the Time to the Most Recent Common Ancestor for the Y chromosome or Mitochondrial DNA for a Pair of ...
		Estimating the Time to the Most Recent Common Ancestor for the Y chromosome or Mitochondrial DNA for a Pair of Individuals
		The posterior distributions for the time to the most recent common ancestor (MRCA) between two individuals assuming 5 (top) and 10 (bottom) marker loci were scored and k matches are observed.
		The increase in the mean and standard deviation (SD) for the time to the MRCA under the stepwise mutational model as compared to the infinite alleles model (Table 1)
	www.genetics.org /cgi/content/full/158/2/897 (5647 words)

	PhyloCode Article 9 (Site not responding. Last check: 2007-09-17)
		A node-based definition may take the form "the clade stemming from the most recent common ancestor of A and B" (and C and D, etc., as needed) or "the least inclusive clade containing A and B" (and C and D, etc.), where A-D are specifiers (see Art.
		Because poorly chosen wordings of phylogenetic definitions can lead to undesirable consequences (i.e., the application of the name in a way that contradicts the author's intent), the wordings provided in Note 9.4.1 should generally be used for the corresponding kinds of definitions.
		If the protologue or subsequent use of the name to which a bibliographic citation refers is part of a publication with consecutive pagination, the page on which the protologue or subsequent use appears should be cited, as opposed to citing only the range of pages of the entire publication.
	www.ohiou.edu /phylocode/art9.html (2194 words)

	ScienceDaily: 'Most Recent Common Ancestor' Of All Living Humans Surprisingly Recent
		Common Genes Form New Family Tree For Animals (June 25, 1999) -- Looking deep within the genes of three very different kinds of animals, scientists have found enough molecular evidence to finally fell the animal kingdom's old family tree.
		New Phylum Sheds Light On Ancestor Of Animals, Humans (November 5, 2006) -- Genetic analysis of an obscure, worm-like creature retrieved from the depths of the North Atlantic has led to the discovery of a new phylum, a rare event in an era when most organisms have already...
		The most impressive idea to emerge from the recent World Economic Summit in Davos, Switzerland: a new approach to identifying and managing the world's twenty most pressing problems.
	www.sciencedaily.com /releases/2004/09/040930122428.htm (1754 words)

	Most recent common ancestor (via CobWeb/3.1 planetlab2.cs.unc.edu) (Site not responding. Last check: 2007-09-17)
		The most recent common ancestor ('''MRCA''') of any set of organisms is the most recent individual which is an ancestor of all of them.
		It is not possible as of 2004 to similarly estimate the time-frame for an actual most recent common ancestor, largely because of the many variables introduced by recombination.
		Jack need not have given thousand good excuses in the bags that lay in the state-room; and as mutiny is forgiven.
	most-recent-common-ancestor.kiwiki.homeip.net.cob-web.org:8888 (150 words)

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