In genetics, the most recent common ancestor (MRCA) of any set of organisms is the most recent individual from which all organisms in the group are directly descended. The term is often applied to human genealogy.

The MRCA of a set of individuals can sometimes be determined by referring to an established pedigree. However, in general, it is impossible to identify the specific MRCA of a large set of individuals, but an estimate of the time at which the MRCA lived can often be given. Such time to MRCA (TMRCA) estimates can be given based on DNA test results and established mutation rates as practiced in genetic genealogy, or by reference to a non-genetic, mathematical model or computer simulation.

The term MRCA is usually used to describe a common ancestor of individuals within a species. It can also be used to describe a common ancestor between species. To avoid confusion, last common ancestor (LCA) or the equivalent term concestor is sometimes used in place of MRCA when discussing ancestry between species.

The term MRCA may also be used to identify a common ancestor between a set of organisms via specific gene pathways. Mitochondrial Eve and Y-chromosomal Adam are examples of such MRCAs. Such genealogies in reality trace ancestry of individual genes, not organisms. As a result, TMRCA estimates for genetic MRCAs are necessarily greater than those for MRCAs of organisms.

MRCA of all living humans[link]

Tracing one person's lineage back in time for a few generations in principle forms a binary tree of parents, grandparents, great-grandparents and so on. However, the number of individuals in an ancestor tree grows exponentially and very soon exceeds the population from which the ancestors were drawn. A human alive today would over 30 generations (going back to about the High Middle Ages), have 2³⁰ or about 1.07 billion ancestors, more than the world population at the time.^[1] Thus it is obvious that there is multiple counting and the individual is descended from some of these ancestors through more than one line: pedigree collapse changes the binary tree to a directed acyclic graph.

Consider the formation, one generation at a time, of the ancestor graph of all living humans with no descendants. Start with living people with no descendants at the bottom of the graph. Adding the parents of all those individuals at the top of the graph will connect (half-) siblings via one or two common ancestors, their parent(s). Adding the next generation will connect all first cousins. As each of the following generations of ancestors is added to the top of the graph, some of the relationships between more and more people are mapped (second cousins, third cousins and so on). Eventually a generation may be reached where one of the many top-level ancestors is the MRCA from whom it is possible to trace a path of direct descendants all the way down to every living person in the bottom generations of the graph.

The MRCA of everyone alive could have co-existed with a large human population, each of whom either has no living descendants or is an ancestor of only some of the people alive today. The existence of an MRCA does therefore not imply the existence of a population bottleneck, let alone a "first couple".

The MRCA of the current population can change over time as new people are born and old ones die.

It is incorrect to assume that the MRCA passed all of his or her genes (or indeed any gene) down to every person alive. Because of sexual reproduction at every generation, an ancestor passes half of his or her genes to each descendant in the next generation. Save for inbreeding, the percentage of genes inherited from the MRCA becomes smaller and smaller in individuals at each generation, sometimes decreasing to zero (at which point the Ship of Theseus paradox arises^[2]), as genes inherited from contemporaries of MRCA are interchanged via sexual reproduction.^[3][4]

Studies have used computer modelling to estimate that the MRCA of modern humans lived between 5,000 to 2,000 years ago.^[4][5]

Identical ancestors point[link]

The MRCA of living humans may have had many companions of both sexes. Many of these contemporaries left direct descendants, but not an unbroken line of descendants all the way down to everyone in today's population. Some contemporaries of the MRCA are ancestors of no one in the current population. The remainder are ancestors of only some of the current population.

Because ancestors of the MRCA are by definition also common ancestors, we can find (less recent) common ancestors by pushing further back in time to ancient common ancestors of all people alive. Eventually we reach a point in the past where all humans can be divided into two groups: those who left no descendants today and those who are common ancestors of all living humans. This point in time is termed the identical ancestors point. Even though each living person receives genes (in original or mutated forms) in dramatically different proportions from these ancestors from the identical ancestors point,^[4] from this point back, all living people share the same set of ancestors, all the way to the first single-celled organism.^[1]

The identical ancestors point for Homo sapiens has been estimated to between 15,000 and 5,000 years ago.^[4][5]

MRCA of different species[link]

Evolutionary tree showing the divergence of modern species from the last universal ancestor in the center.^[6] The three domains are colored, with bacteria blue, archaea green, and eukaryotes red.

It is also possible to use the term MRCA to describe the common ancestor of two or more different species. In the past, the term MRCA was used interchangeably with last common ancestor (LCA) to denote both the common ancestor within a species and that between species. But MRCA is now more frequently used to describe common ancestors within a species. On the other hand, LCA now describes the common ancestor between two species.

The concept of the last common ancestor is described in Richard Dawkins' book, The Ancestor's Tale, in which he imagines a 'pilgrimage' backwards in time, during which we humans travel back through our own evolutionary history and as we do so are joined at each successive stage by all the other species of organism with which we share each respective common ancestor. Dawkins uses the word "concestor" (coined by Nicky Warren) as an alternative to LCA.

In The Ancestor's Tale, following the human evolutionary tree backwards, we first meet the concestor which we share with the species that are our closest relatives, the chimpanzee and bonobo. Dawkins estimates this to have occurred between 5 and 7 million years ago. Another way of looking at this is to say that our (approximately) 250,000-greats-grandparent was a creature from which all humans, chimpanzees and bonobos are directly descended. Further on in Dawkins' imaginary journey (imaginary, in that the journey is going backwards in time), we meet the concestor we share with the gorilla, our next nearest relative, then the orangutan, and so on, until we finally meet the concestor of all living organisms, known as the last universal ancestor.

A common mistake made by the public as well as some authors is to refer to a proposed last common ancestor as an earliest ancestor. Examples include the book The Link: Uncovering Our Earliest Ancestor by Colin Tudge,^[7] and a documentary of the same name screened on the History Channel (US) and BBC One (UK),^[8] both referring to the primate fossil dubbed Ida.

MRCA of a population identified by a single genetic marker[link]

It is also possible to consider the ancestry of individual genes (coalescent theory), instead of a person (an organism) as a whole. Unlike organisms, a gene is passed down from a generation of organisms to the next generation either as perfect replicas of itself or as slightly mutated descendant genes. While organisms have ancestry graphs and progeny graphs via sexual reproduction, a gene has a single chain of ancestors and a tree of descendants. An organism produced by sexual, allogamous reproduction has at least two ancestors (immediate parents), but a gene always has one single ancestor.

Given any gene in the body of a person, we can trace a single chain of human ancestors back in time, following the lineage of this one gene. Because a typical organism is built from tens of thousands of genes, there are numerous ways to trace the ancestry of organisms using this mechanism. But all these inheritance pathways share one common feature. If we start with all humans alive in 1995 and trace their ancestry by one particular gene (actually a locus), we find that the farther we move back in time, the smaller the number of ancestors becomes. The pool of ancestors continues to shrink until we find the most recent common ancestor (MRCA) of all humans who were alive in 1995, via this particular gene pathway.^[1]

Patrilineal and matrilineal MRCA[link]

Mitochondrial DNA (mtDNA) is nearly immune to sexual mixing, unlike the nuclear DNA whose chromosomes are shuffled and recombined in Mendelian inheritance. Mitochondrial DNA, therefore, can be used to trace matrilineal inheritance and to find the Mitochondrial Eve (also known as the African Eve), the most recent common ancestor of all humans via the mitochondrial DNA pathway.

Similarly Y chromosome is present as a single sex chromosome in the male individual and is passed on to male descendants without recombination. It can be used to trace patrilineal inheritance and to find the Y-chromosomal Adam, the most recent common ancestor of all humans via the Y-DNA pathway.

Mitochondrial Eve and Y-chromosomal Adam have been established by researchers using genealogical DNA tests. Mitochondrial Eve is estimated to have lived about 140,000 years ago. Y-chromosomal Adam is estimated to have lived around 60,000 years ago. The MRCA of humans alive today would therefore need to have lived more recently than either.^[3][9]

It is more complicated to infer human ancestry via autosomal chromosomes. Although an autosomal chromosome contains genes that are passed down from parents to children via independent assortment from only one of the two parents, genetic recombination (chromosomal crossover) mixes genes from non-sister chromatids from both parents during meiosis, thus changing the genetic composition of the chromosome.

Time to MRCA estimates[link]

Different types of MRCAs are estimated to have lived at different times in the past. These time to MRCA (TMRCA) estimates are also computed differently depending on the type of MRCA being considered. Patrilineal and matrilineal MRCAs (Mitochondrial Eve and Y-chromosomal Adam) are traced by single gene markers, thus their TMRCA are computed based on DNA test results and established mutation rates as practiced in genetic genealogy. Time to genealogical MRCA of all living humans is computed based on non-genetic, mathematical models and computer simulations.

Since Mitochondrial Eve and Y-chromosomal Adam are traced by single genes via a single ancestral parent lines, the time to these genetic MRCAs will necessarily be greater than that for the genealogical MRCA. This is because single genes will coalesce slower than tracing of conventional human genealogy via both parents. The latter considers only individual humans, without taking into account whether any gene from the computed MRCA actually survives in every single person in the current population.^[10]

TMRCA via genetic markers[link]

Mitochondrial DNA can be used to trace the ancestry of a set of populations. In this case, populations are defined by the accumulation of mutations on the mtDNA, and special trees are created for the mutations and the order in which they occurred in each population. The tree is formed through the testing of a large number of individuals all over the world for the presence or lack of a certain set of mutations. Once this is done it is possible to determine how many mutations separate one population from another. The number of mutations, together with estimated mutation rate of the mtDNA in the regions tested, allows scientists to determine the approximate time to MRCA (TMRCA) which indicates time passed since the populations last shared the same set of mutations or belonged to the same haplogroup.

In the case of Y-Chromosomal DNA, TMRCA is arrived at in a different way. Y-DNA haplogroups are defined by single-nucleotide polymorphism in various regions of the Y-DNA. The time to MRCA within a haplogroup is defined by the accumulation of mutations in STR sequences of the Y-Chromosome of that haplogroup only. Y-DNA network analysis of Y-STR haplotypes showing a non-star cluster indicates Y-STR variability due to multiple founding individuals. Analysis yielding a star cluster can be regarded as representing a population descended from a single ancestor. In this case the variability of the Y-STR sequence, also called the microsatellite variation, can be regarded as a measure of the time passed since the ancestor founded this particular population. The descendants of Genghis Khan or one of his ancestors represents a famous star cluster that can be dated back to the time of Genghis Khan.^[11]

TMRCA calculations are considered critical evidence when attempting to determine migration dates of various populations as they spread around the world. For example, if a mutation is deemed to have occurred 30,000 years ago, then this mutation should be found amongst all populations that diverged after this date. If archeological evidence indicates cultural spread and formation of regionally isolated populations then this must be reflected in the isolation of subsequent genetic mutations in this region. If genetic divergence and regional divergence coincide it can be concluded that the observed divergence is due to migration as evidenced by the archaeological record. However, if the date of genetic divergence occurs at a different time than the archaeological record, then scientists will have to look at alternate archaeological evidence to explain the genetic divergence. The issue is best illustrated in the debate surrounding the demic diffusion versus cultural diffusion during the European Neolithic.^[12]

TMRCA of all living humans[link]

Estimating time to MRCA of all humans based on the common genealogical usage of the term 'ancestor' is much harder and less accurate compared to estimates of Patrilineal and matrilineal MRCAs. Researchers must trace ancestry along both female and male parental lines, and rely on historical and archaeological records.

Depending on the survival of isolated lineages without admixture from modern migrations and taking into account long-isolated peoples, such as historical societies in central Africa, Australia and remote islands in the South Pacific, the human MRCA was generally assumed to have lived in the Upper Paleolithic period. With the advent of mathematical models and computer simulations, researchers now find that the MRCA of all humans lived remarkably recently, between 2,000 and 4,000 years ago.^{[citation needed]}

Rohde, Olson and Chang (2004) constructed a mathematical model that considered the tendency of individuals to choose mates from the same group, as well as the relative geographical isolation of such groups.^[4] The mathematical model with one particular set of parameters showed that the MRCA lived about the year 300 BC and yielded an identical ancestor point (IAP) of 3,000 BC.

The same 2004 Rohde paper also presented results from a computer program based on Monte Carlo simulation designed to overcome some of the limits of the mathematical model. The program took into consideration realistic population substructure and migration patterns, allowing the researchers to simulate historical human demography. A conservative simulation yielded a mean MRCA date of 1,415 BC and a mean IA date of 5,353 BC. A less conservative simulation gave an MRCA date of AD 55 and an IA date of 2,158 BC.^[4]

An explanation of this recent MRCA date 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 remote habitats. The possibility remains that an isolated population with no recent "mainland" admixture persists somewhere, which would immediately push back the date of humanity's MRCA by many millennia. While simulations help estimate probabilities, the question can be resolved only by genetically testing every living human individual.

An assumption that there are no isolated populations is questionable in view of the existence of various uncontacted peoples, who are suspected to have been isolated for many millennia, including the Sentinelese who have been isolated from the western world and also from the Asian mainland.

See also[link]

Evolutionary biology portal

• Clade - a group consisting of an organism and all its descendants
• Coalescent theory - a retrospective model of population genetics
• Genealogy - the study of families and the tracing of their lineages and history
• Genetic distance - the genetic divergence between species or between populations within a species
• Genetic genealogy - the application of genetics to traditional genealogy
• Genealogical DNA tests - examination of nucleotides at specific locations on a person's DNA for genetic genealogy purposes
• Lowest common ancestor - an analogous concept in graph theory and computer science
• Phylogenetic tree - a branching diagram or "tree" showing the inferred evolutionary relationships among various biological species
• Timeline of evolution - outlines the major events in the development of life on the planet Earth
• Timeline of human evolution - outlines the major events in the development of human species

References[link]

Further reading[link]

• Hartwell, Leland (2004). Genetics: From Genes to Genomes (2nd ed.). Maidenhead: McGraw-Hill. ISBN 0-07-291930-2. 
• Walsh B (June 2001). "Estimating the time to the most recent common ancestor for the Y chromosome or mitochondrial DNA for a pair of individuals". Genetics 158 (2): 897–912. PMC 1461668. PMID 11404350. http://www.genetics.org/cgi/reprint/158/2/897.pdf. 

External links[link]

Documentaries

• DNA Mysteries – The Search for Adam – by Spencer Wells – National Geographic, 2008
• The Real Eve: Modern Man's Journey Out of Africa – by Stephen Oppenheimer – Discovery Channel, 2002
• Journey of Man: A Genetic Odyssey (movie) by Spencer Wells – PBS and National Geographic Channel, 2003

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Evolutionary Biology
Key topics Introduction to evolution Common descent Evidence of common descent
Processes and outcomes Population genetics Variation • Mutation Natural selection • Adaptation Polymorphism (biology) Genetic drift • Gene flow Speciation • Adaptive radiation Co-operation • Coevolution Divergent • Convergent Parallel evolution Extinction
Natural history Origin of Life • History of life Timeline of evolution Human evolution Phylogeny Biodiversity • Biogeography Classification • Cladistics Transitional fossil Extinction event
History of evolutionary theory Overview Timeline of paleontology History of paleontology Renaissance and Enlightenment Before Darwin Darwin • On the Origin of Species Before the Synthesis Modern evolutionary synthesis Molecular evolution • Evo-devo Current research
Fields and applications Applications of evolution Artificial selection Biosocial criminology Ecological genetics Evolutionary aesthetics Evolutionary anthropology Evolutionary computation Evolutionary economics Evolutionary ethics Evolutionary game theory Evolutionary linguistics Evolutionary medicine Evolutionary neuroscience Evolutionary physiology Evolutionary psychology Experimental evolution Phylogenetics Systematics Universal Darwinism
Social implications Theory and fact Social effect Controversy Objections Level of support
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In evolutionary biology, a group of organisms share common descent if they have a common ancestor. There is strong quantitative support for the theory that all living organisms on Earth are descended from a common ancestor.^[1][2]

Charles Darwin proposed the theory of universal common descent through an evolutionary process in On the Origin of Species, twice stating the hypothesis that there was only one progenitor for all life forms and ending with "There is a grandeur in this view of life, with its several powers, having been originally breathed into a few forms or into one".^[3] The theory asserts that all currently living organisms on Earth share a common genetic heritage with each being the descendant from a single original species, though the suggestion of substantial horizontal gene transfer during early evolution has led to questions about monophyly of life.^[1]

The last universal ancestor (LUA) (also called the last universal common ancestor, LUCA), that is, the most recent common ancestor of all currently living organisms,^[1] is believed to have appeared about 3.9 billion years ago.^[4][5]

History[link]

In the 1740s, Pierre-Louis Moreau de Maupertuis made the first known suggestion in a series of essays that all organisms may have had a common ancestor, and that they had diverged through random variation and natural selection.^[6][7] In Essai de Cosmologie, Maupertuis noted:

Could one not say that, in the fortuitous combinations of the productions of nature, as there must be some characterized by a certain relation of fitness which are able to subsist, it is not to be wondered at that this fitness is present in all the species that are currently in existence? Chance, one would say, produced an innumerable multitude of individuals; a small number found themselves constructed in such a manner that the parts of the animal were able to satisfy its needs; in another infinitely greater number, there was neither fitness nor order: all of these latter have perished. Animals lacking a mouth could not live; others lacking reproductive organs could not perpetuate themselves ... The species we see today are but the smallest part of what blind destiny has produced ...^[8]

In 1790, Immanuel Kant wrote in Kritik der Urtheilskraft (Critique of Judgement) that the analogy of animal forms implies a common original type, and thus a common parent.^[9]

In 1795, Charles Darwin's grandfather, Erasmus Darwin, asked:

[W]ould it be too bold to imagine, that in the great length of time, since the earth began to exist, perhaps millions of ages before the commencement of the history of mankind, would it be too bold to imagine, that all warm-blooded animals have arisen from one living filament, which the great First Cause endued with animality, with the power of acquiring new parts attended with new propensities, directed by irritations, sensations, volitions, and associations; and thus possessing the faculty of continuing to improve by its own inherent activity, and of delivering down those improvements by generation to its posterity, world without end?^[10]

In 1859, Charles Darwin's The Origin of Species was published. The views about common descent expressed therein were that it was possible that there was only one progenitor for all life forms.

"Therefore I should infer from analogy that probably all the organic beings which have ever lived on this earth have descended from some one primordial form, into which life was first breathed." ^[3] (p 484)

Darwin's famous closing sentence describes the "grandeur in this view of life, with its several powers, having been originally breathed into a few forms or into one."^[3] (p 490)

Evidence of universal common descent[link]

Common biochemistry and genetic code[link]

All known forms of life are based on the same fundamental biochemical organisation: genetic information encoded in DNA, transcribed into RNA, through the effect of protein- and RNA-enzymes, then translated into proteins by (highly similar) ribosomes, with ATP, NADH and others as energy sources, etc. Furthermore, the genetic code (the "translation table" according to which DNA information is translated into proteins) is nearly identical for all known lifeforms, from bacteria to humans. The universality of this code is generally regarded by biologists as definitive evidence in favor of the theory of universal common descent. Analysis of the small differences in the genetic code has also provided support for universal common descent.^[11] A statistical comparison of various alternative hypotheses has shown that universal common ancestry is significantly more probable than models involving multiple origins.^[1][12]

Selectively neutral similarities[link]

Similarities which have no adaptive relevance cannot be explained by convergent evolution, and therefore they provide compelling support for the theory of universal common descent.

Such evidence has come from two areas: amino acid sequences and DNA sequences. Proteins with the same three-dimensional structure need not have identical amino acid sequences; any irrelevant similarity between the sequences is evidence for common descent. In certain cases, there are several codons (DNA triplets) that code for the same amino acid. Thus, if two species use the same codon at the same place to specify an amino acid that can be represented by more than one codon, that is evidence for a recent common ancestor.

Other similarities[link]

The universality of many aspects of cellular life is often pointed to as supportive evidence to the more compelling evidence listed above. These similarities include the energy carrier adenosine triphosphate (ATP), and the fact that all amino acids found in proteins are left-handed. It is, however, possible that these similarities resulted because of the laws of physics and chemistry, rather than universal common descent and therefore resulted in convergent evolution.

Phylogenetic trees[link]

A phylogenetic tree based on rRNA genes.

Another important piece of evidence is that it is possible to construct detailed phylogenetic trees (that is, "genealogic trees" of species) mapping out the proposed divisions and common ancestors of all living species. In 2010 an analysis of available genetic data, mapping them to phylogenetic trees, gave "firm quantitative support for the unity of life. ...there is now strong quantitative support, by a formal test,^[1] for the unity of life.^[2] It should be noted, however, the 'formal' test is criticised^[13] for not including consideration of convergent evolution, and Theobald has defended the method against this claim.^[14][15]

Traditionally, these trees have been built using morphological methods, such as appearance, embryology, etc. Recently, it has been possible to construct these trees using molecular data, based on similarities and differences between genetic and protein sequences. All these methods produce essentially similar results, even though most genetic variation has no influence over external morphology. That phylogenetic trees based on different types of information agree with each other is strong evidence of a real underlying common descent.^[16]

Illustrations of common descent[link]

Artificial selection[link]

Artificial selection demonstrates the diversity that can exist among organisms that share a relatively recent common ancestor. In artificial selection, one species is bred selectively at each generation, allowing only those organisms that exhibit desired characteristics to reproduce. These characteristics become increasingly well-developed in successive generations. Artificial selection was successful long before science discovered the genetic basis.

The Chihuahua mix and Great Dane illustrate the range of sizes among dog breeds.

Dog breeding[link]

The diversity of domesticated dogs is an example of the power of artificial selection. All breeds share common ancestry, having descended from wolves. Humans selectively bred them to enhance specific characteristics, such as color and length or body size. This created a range of breeds that include the Chihuahua, Great Dane, Basset Hound, Pug, and Poodle. Wild wolves, which did not undergo artificial selection, are relatively uniform in comparison.

Wild cabbage[link]

Wild Cabbage plant

Early farmers cultivated many popular vegetables from the Brassica oleracea (wild cabbage) by artificially selecting for certain attributes. Common vegetables such as cabbage, kale, broccoli, cauliflower, kohlrabi and Brussels sprouts are all descendants of the wild cabbage plant.^{[17][page needed]} Brussels sprouts were created by artificially selecting for large bud size. Broccoli was bred by selecting for large flower stalks. Cabbage was created by selecting for short petioles. Kale was bred by selecting for large leaves.

Natural selection[link]

Darwin's finches

Natural selection is the evolutionary process by which heritable traits that increase an individual's fitness become more common, and heritable traits that decrease an individual's fitness become less common.

Darwin's finches[link]

During Charles Darwin's studies on the Galápagos Islands, Darwin observed 13 species of finches that are closely related and differ most markedly in the shape of their beaks. The beak of each species is suited to the food available in its particular environment, suggesting that beak shapes evolved by natural selection. Large beaks were found on the islands where the primary source of food for the finches are nuts and therefore the large beaks allowed the birds to be better equipped for opening the nuts and staying well nourished. Slender beaks were found on the finches which found insects to be the best source of food on the island they inhabited; their slender beaks allowed the birds to be better equipped for pulling out the insects from their tiny hiding places. The finch is also found on the main land and it is thought that they migrated to the islands and began adapting to their environment through natural selection.

See also[link]

	Book: Evolution
Wikipedia books are collections of articles that can be downloaded or ordered in print.

References[link]

External links[link]

• 29+ Evidences for Macroevolution: the Scientific Case for Common Descent. From the TalkOrigins Archive
• The Tree of Life Web Project

Lloyd Anthony Pye (born 1946)^[1] is an American author best known for his promotion of the Starchild skull, which Pye claims is the relic skull of a human-alien hybrid.

Writing[link]

His first book That Prosser Kid (1977), a fictional account of college football, was said to have "achieved considerable recognition" by the Continuum Encyclopedia of American Literature,^[2] but was called "lively but unoriginal" by the Boston Globe.^[3] His 1988 book Mismatch was called a "novel that ought to go on your must read list" by Deseret News.^[4]

In addition to authoring books, Pye also gives lectures and has made television appearances in support of his ideas on The Learning Channel, National Geographic Channel, Extra, Animal Planet, and Richard & Judy in the United Kingdom.^[5] Pye has stated that he believes Bigfoot exists.^[6]

The Starchild skull[link]

In the late 1990s, Pye obtained a curiously shaped skull from a couple in El Paso, Texas that he believes is an alien-human hybrid and proof that humans are descended from extra-terrestrial beings he calls "terraformers".^[7] DNA tests show that the skull is from a human male. American clinical neurologist Steven Novella believes the skull belongs to a child who suffered from hydrocephalus.^[8][9]

Books[link]

• That Prosser Kid (fiction, Arbor House, 1977, ISBN 0-87795-165-9) about a redshirted college football player,^[10] republished as A Darker Shade of Red (2007, Bell Lap Books)^[11]
• Mismatch, (fiction, Dell, 1988), about computer hacking and warfare.^[12]
• Everything You Know is Wrong – Book One: Human Evolution
• The Starchild Skull
• Starchild Skull Essentials

Personal life[link]

Pye was born in Houma, Louisiana, to Lloyd A. Pye Sr., an optometrist (died 2007), and Nina, and he had three brothers.^[13][14] He earned a football scholarship to Tulane University, New Orleans as a Running back/Punter from 1964–1968.^[15][16] He was Tulane's leading punter 1967-8.^[17] He graduated in 1968 with a B.S. in psychology, and joined the U.S. Army as a military intelligence specialist.^[13]

He lives in Pensacola as of 2007,^[14][18] and is married to Amy.^[14][19]

References[link]

External links[link]

• Lloyd Pye's website
• Bibliography of Pye, Lloyd, isbndb.com

Spencer Wells
Spencer Wells
Born	(1969-04-06) April 6, 1969 (age 43) Georgia, United States
Citizenship	American
Fields	Genetics
Alma mater	University of Texas at Austin Harvard University
Notable awards	Kistler Prize (2007)

Spencer Wells (born April 6, 1969 in Georgia, United States) is a geneticist and anthropologist, an Explorer-in-Residence at the National Geographic Society, and Frank H.T. Rhodes Class of '56 Professor at Cornell University. He leads The Genographic Project.

Education[link]

Wells grew up in Lubbock, Texas.^[1] He obtained a Bachelor of Science in Biology from the University of Texas at Austin in 1988, and a Ph.D. in Biology from Harvard University in 1994. He was a postdoctoral fellow at Stanford University between 1994 and 1998, and a research fellow at Oxford University between 1999 and 2000.

Work[link]

Spencer Wells at the TED Global conference in Arusha, Tanzania in 2007

Wells did his Ph.D. work under Richard Lewontin, and later did postdoctoral research with Luigi Luca Cavalli-Sforza and Sir Walter Bodmer. His work, which has helped to establish the critical role played by Central Asia in the peopling of the world, has been published in journals such as Science, American Journal of Human Genetics, and the Proceedings of the National Academy of Sciences.

He wrote the book The Journey of Man: A Genetic Odyssey (2002),^[2] which explains how genetic data has been used to trace human migrations over the past 50,000 years, when modern humans first migrated outside of Africa. According to Wells, one group took a southern route and populated southern India and southeast Asia, then Australia. The other group, accounting for 90% of the world's non-African population (some 5 billion people as of late 2006), took a northern route, eventually peopling most of Eurasia (largely displacing the aboriginals in southern India, Sri Lanka and Southeast Asia in the process), North Africa and the Americas. Wells also wrote and presented the PBS/National Geographic documentary of the same name. By analyzing DNA from people in all regions of the world, Wells has concluded that all humans alive today are descended from a single man who lived in Africa around 60,000 - 90,000 years ago, a man also known as Y-chromosomal Adam.^[3]

Since 2005, Wells has headed The Genographic Project, undertaken by the National Geographic Society, IBM, and the Waitt Family Foundation,^[4] which aims to creating a picture of how our ancestors populated the planet by analyzing DNA samples from around the world.^[5] He presents the knowledge gained from the project around the world, including at the 2007 TED conference, where he spoke specifically about human diversity.^[6]

He is quoted as saying: "As often happens in science, technology has opened up a field to new ways of answering old questions—often providing startling answers."^[7]

As director of the Genographic Project he said this about the possibility of two human species living today together: "We don't know how long it takes for hominids to fission off into separate species, but clearly they were separated for a very long time" ^[8] This question may be estimated by comparing other species with similar speed of reproduction.^[9]

He was a keynote speaker at the Science & Technology Summit in The Hague on November 18, 2010. Wells also gave the keynote address at the University of Texas College of Natural Sciences commencement exercises on May 21, 2011.

Awards[link]

• National Merit Scholar
• Phi Beta Kappa
• Howard Hughes Medical Institute Predoctoral Fellowship
• Alfred P. Sloan Foundation Postdoctoral Fellowship
• Fellow of The Explorers Club
• Kistler Prize
• Outstanding Young Texas Ex

Books[link]

• The Journey of Man: A Genetic Odyssey, 2002 (Penguin, UK; Princeton University Press and Random House, US; Fischer Verlag, Germany; Longanesi, Italy; Oceano, Spain/Latin America; Ucila International, Slovenia; Dokoran, Czech Republic; Akkord, Hungary; Oriental Press, China; Basilico, Japan; ScienceBooks, Korea; Yurt, Turkey; CD Press, Romania; Alpina, Russia)
• Deep Ancestry: Inside the Genographic Project, 2006 (National Geographic)
• Pandora's Seed: The Unforeseen Cost of Civilization,^[10] 2010 (Random House, US; Penguin, UK; Contact, Netherlands; Codice, Italy; Eksmo, Russia; Nika Center, Ukraine; Commonwealth, Taiwan; Eulyoo, Korea; Kagaku-Dojin, Japan; Shanghai BBT, China)

Films[link]

• 2000 - The Difference (Channel Four, UK)
• 2002 - The Real King and Queen (Discovery Channel)
• 2003 - Journey of Man (PBS/National Geographic Channel) - CINE Golden Eagle award
• 2004 - Quest for the Phoenicians (PBS)
• 2005 - Search for Adam (National Geographic Channel)
• 2007 - China's Secret Mummies (National Geographic Channel) - nominated for Outstanding Historical Programming Emmy
• 2009 - The Human Family Tree (National Geographic Channel) - nominated for Outstanding Science and Technology Programming Emmy

See also[link]

• Recent single-origin hypothesis
• Y-chromosomal Adam
• The Genographic Project

References[link]

External links[link]

Wikimedia Commons has media related to: Spencer Wells

• Spencer Wells on Facebook
• Spencer Wells on Twitter
• Spencer Wells at the Internet Movie Database
• EurAsia '98 expedition website
• The Genographic Project
• Interview on the University of Texas website
• Article from the December 2004 issue of Discover
• Interview in PLoS Genetics