Mitochondrial DNA tree calibrated with ancient DNA

Clocking the Human Exodus Out of Africa

The team analyzed 10 well-dated fossils, including a medieval man who lived in France 700 years ago; the 4550-year-old Iceman; two 14,000-year-old skeletons from the tombs of Oberkassel in Germany; three related, modern humans from 31,000 years ago in Dolni Vestonice in the Czech Republic; and an early modern human from 40,000 years ago in Tianyuan, China. [. . .]

The team's method for checking the mutation rate is clever, says geneticist Aylwyn Scally of the Wellcome Trust Sanger Institute in Hinxton, U.K., co-author of one of the studies that calculated the slower mutation rate in living humans. "It's excellent that they have been able to get a better baseline for calibrating the mtDNA mutation rate by looking at ancient DNA."

However, Scally notes, mtDNA is a single genetic lineage, which is not typical of the genome, partly because the mutation rate of mtDNA could be higher because it has a higher proportion of genes under selection than the entire nuclear genome. Krause and one of his collaborators, paleogeneticist Svante Pääbo of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, agree that future work will be needed to resolve the differences in mutation rates in the mtDNA and nuclear genomes. "It is possible that there are things we do not understand about mitochondrial inheritance and mutation patterns," Pääbo says. [. . .]

And that matters, Krause says, because a sense of timing is critical in human evolution. Knowing when modern humans spread out of Africa and into Europe and Asia, for example, allowed Krause and his collaborators to show that the same modern humans were in Europe before and after the glaciers covered that continent—and had the ability to adapt to changing climates. They found that modern humans before and after the last major ice age in Europe share the same mtDNA lineage, making them direct descendants of the same linage. "Out of Africa is one of the major events within human evolution," Krause says. "We need to know when it happened."

The paper:

A Revised Timescale for Human Evolution Based on Ancient Mitochondrial Genomes

Qiaomei Fu, Alissa Mittnik, Philip L.F. Johnson, Kirsten Bos, Martina Lari, Ruth Bollongino, Chengkai Sun, Liane Giemsch, Ralf Schmitz, Joachim Burger, Anna Maria Ronchitelli, Fabio Martini, Renata G. Cremonesi, Jir(í Svoboda, Peter Bauer, David Caramelli, Sergi Castellano, David Reich, Svante Pääbo, Johannes Krause

Background

Recent analyses of de novo DNA mutations in modern humans have suggested a nuclear substitution rate that is approximately half that of previous estimates based on fossil calibration. This result has led to suggestions that major events in human evolution occurred far earlier than previously thought. Results

Here, we use mitochondrial genome sequences from ten securely dated ancient modern humans spanning 40,000 years as calibration points for the mitochondrial clock, thus yielding a direct estimate of the mitochondrial substitution rate. Our clock yields mitochondrial divergence times that are in agreement with earlier estimates based on calibration points derived from either fossils or archaeological material. In particular, our results imply a separation of non-Africans from the most closely related sub-Saharan African mitochondrial DNAs (haplogroup L3) that occurred less than 62–95 kya.

Conclusions

Though single loci like mitochondrial DNA (mtDNA) can only provide biased estimates of population divergence times, they can provide valid upper bounds. Our results exclude most of the older dates for African and non-African population divergences recently suggested by de novo mutation rate estimates in the nuclear genome. [. . .]

We were able to reconstruct three complete and six nearly complete mitochondrial genomes from ancient human remains that were found in Europe and Eastern Asia and span 40,000 years of human history. All Paleolithic and Mesolithic European samples belong to mtDNA hg U, as was previously suggested for pre-Neolithic Europeans [15]. Two of the three individuals from the Dolni Vestonice triple burial associated with the pre-ice age Gravettian culture, namely, 14 and 15, show identical mtDNAs, suggesting a maternal relationship. Furthermore, both individuals display a mitochondrial sequence that falls basal in a phylogenetic tree compared to the post-ice age hunter-gatherer samples from Italy and central Europe, as well as the contemporary mtDNA hg U5 (Figure 1). It has been argued that hg U5 is the most ancient subhaplogroup of the U lineage, originating among the first early modern humans in Europe [18]. Our results support this hypothesis because we find that the two Dolni Vestonice individuals radiocarbon dated to 31.5 kya carry a type of mtDNA that is as yet uncharacterized, sits close to the root of hg U, and carries two mutations that are specific to hg U5. With our recalibrated molecular clock, we date the age of the U5 branch to approximately 30 kya, thus predating the LGM. Because the majority of late Paleolithic and Mesolithic mtDNAs analyzed to date fall on one of the branches of U5 (see also [15]), our data provide some support for maternal genetic continuity between the pre- and post-ice age European hunter-gatherers from the time of first settlement to the onset of the Neolithic. U4, another hg commonly found in Mesolithic hunter-gatherers [15], has so far not been sequenced in a Paleolithic individual, and we find hgs U8 and U2 in pre-LGM individuals but not in later hunter-gatherers. At present, the genetic data on Upper Paleolithic, and especially pre-ice age, populations are too sparse to comment on whether or not this is representative of a change in the genetic structure of the population, perhaps caused by a bottleneck during the LGM and a subsequent repopulation from glacial refugia.

James Neel and early human population structure

A recent study: An Enlarged Parietal Foramen in the Late Archaic Xujiayao 11 Neurocranium from Northern China, and Rare Anomalies among Pleistocene Homo

The press release: Skulls of early humans carry telltale signs of inbreeding, study says

Buried for 100,000 years at Xujiayao in the Nihewan Basin of northern China, the recovered skull pieces of an early human exhibit a now-rare congenital deformation that indicates inbreeding might well have been common among our ancestors, new research from the Chinese Academy of Sciences and Washington University in St. Louis suggests. [. . .]

Traces of genetic abnormalities, such as EPF, are seen unusually often in the skulls of Pleistocene humans, from early Homo erectus to the end of the Paleolithic.

"The probability of finding one of these abnormalities in the small available sample of human fossils is very low, and the cumulative probability of finding so many is exceedingly small," suggests study co-author Erik Trinkaus, the Mary Tileston Hemenway Professor of Anthropology in Arts & Sciences at Washington University in St. Louis.

"The presence of the Xujiayao and other Pleistocene human abnormalities therefore suggests unusual population dynamics, most likely from high levels of inbreeding and local population instability." It therefore provides a background for understanding populational and cultural dynamics through much of human evolution.

Some related comments from James V. Neel's 1994 autobiography:

With our long-established interests in inbreeding, it was inevitable that we should try to establish how frequent it was amongst Amerindians. The Yanomama recognize male-descent lineages; a man should marry outside his lineage. A highly preferred for of marriage is for men of two lineages to exchange younger sisters as brides. In the following generation, the female offspring of such an exchange must marry outside the lineage. [. . .] Thus, the preferred marriage involves certain types of first cousins. When such a marriage is not possible, a man (or a woman) will try to marry within the village, which of course contains many of the man's more remote kin. This marriage system, if observed, should result in a high level of inbreeding. [. . .] Despite Chagnon's best effort, he could only establish the identity of the 4 grandparents in 37 of the 124 marriages represented in the 4 villages where he new the genealogies best. Thirteen of these 34 marriages involved first cousins. This was a high frequency, but was it representative? Again, we resorted to computer simulation, to try to determine how rapidly inbreeding would build up under these circumstances. The answer was, quite rapidly, by our contemporary standards. The key was the small geographical extent of the marital quest and the differential fertility we have just discussed. For instance, the "grandchildren" of the more prolific headmen would all be first cousins, and they would be concentrated in several adjacent villages.

We believe that the level of inbreeding that we encountered in the Yanomama was not a recent development, but one that goes far back in time. Accordingly, aided by the computer program, we could ask the question, if this pattern of inbreeding was in place when the Indian entered the Americas, just how inbred had these populations become by now? Our best estimate was that the average marriage in an Indian village represented a level of inbreeding at least five times as large as the inbreeding in a first-cousin marriage. This is, in fact, greater than the inbreeding in a brother-sister union. This conclusion was so surprising that we have gone back to reexamine it from every possible vantage point, and from every possible vantage point it seems to hold. [. . .]

A second obvious genetic departure of most of the civilized world from tribal societies is the relaxation of inbreeding. A discussion of the consequences of such relaxation rapidly becomes complex, and we will consider only the simplest case, involving diseases due to completely recessive genes with quite deleterious effects, incompatible with reproduction. [. . .] When inbreeding is relaxed, as is now particularly the case for Christian communities, homozygosity for genes of this type decreases, and there should be a decrease in the diseases associated with these genes. This, however, is only temporary. Mutation pressure continues, and the gene frequency will very slowly build up, until finally the frequency of homozygotes will again come into balance with mutation pressure. However, the relative frequency of the heterozygotes in the population is now greater than before. Should this population ever revert to high levels of inbreeding, it would, so to speak, "pay the bill," i.e., the gene frequency would have risen above the frequency consistent with the new level of inbreeding, and there would now temporarily be more of whatever disease is associated with the genes in question than would be the case had inbreeding continued at the original levels. Furthermore, there is evidence from experimental genetics that the heterozygotes for these recessive genes are sometimes themselves slightly disadvantaged, so that a relative increase in the frequency of the heterozygous carriers of a deleterious recessive gene is not to the advantage of the population.

[Physician to the Gene Pool, pp. 184-188]

More from Neel:

"De-Extinction" startup and embryo screening

"By reviving lost species, a new company could put a warm and fuzzy face on advanced reproductive engineering":

Two of biotechnology’s most prolific and far-sighted researchers say they’re teaming up to start a company that intends to rewrite the rules of animal reproduction.

The company, provisionally named Ark Corporation, is being cofounded by stem-cell pioneer Robert Lanza and Harvard Medical School DNA expert George Church. [. . .]

But here’s the deal: the very same biotechnologies needed to reanimate lost species are going to have far, far greater financial and social impact when they’re applied to commercial breeding of livestock, pets, and even humans. [. . .]

Ark’s key technology is going to be induced pluripotent stem cells, or iPS cells (see “Growing Heart Cells Just for You”). To make iPS cells, researchers take an ordinary skin cell and, by modifying it or adding certain chemicals, turn it into a potent stem cell that’s able to grow into any other tissue of the body, including eggs and sperm.

It’s exactly this ability to make sperm and eggs in the lab that opens the commercial possibilities Lanza and Church say their startup company will exploit. [. . .]

Beyond farm animals, iPS cells have even more mind-boggling possibilities in human reproduction. With this technology, it may be possible to create functional eggs and sperm for people who are infertile because of age or other issues.

Note that in the China Is Engineering Genius Babies stories statements like "embryo screening will allow parents to pick their brightest zygote and potentially bump up every generation's intelligence by five to 15 IQ points" refer to what's plausible with current IVF technology. Here, a relatively restricted number of embryos would be produced; they'd be sequenced or genotyped; and estimates of genomic IQ or other traits of interest would be used in choosing one or two of the embryos to implant. Again, there's nothing (beyond presently insufficient sample sizes) that prevents this from happening with our current understanding of genetics and existing reproductive technology.

Projecting forward very minimally, if it becomes possible to effectively and cheaply produce hundreds or thousands of eggs from skin cells, besides likely increasing the uptake of IVF with embryo screening by couples with normal fertility (ovarian hyperstimulation, etc., is not something I expect most women would rush to volunteer for in exchange for the promise their children will average 5 points higher in IQ) it should make possible much higher levels of selection per generation. A similar and potentially even greater increase in selective power might come from genetic screening of individual sperm cells prior to fertilization, which has now been demonstrated in mice. Beyond IQ, it should be similarly straightforward to select for any other heritable quantitative trait or for combinations of traits (height, longevity, physical ability, etc.).

"Common DNA Markers Can Account for More Than Half of the Genetic Influence on Cognitive Abilities"

A new paper from Robert Plomin (full text is free), reiterating a point that some are still failing to grasp:

For nearly a century, twin and adoption studies have yielded substantial estimates of heritability for cognitive abilities, although it has proved difficult for genomewide-association studies to identify the genetic variants that account for this heritability (i.e., the missing-heritability problem). However, a new approach, genomewide complex-trait analysis (GCTA), forgoes the identification of individual variants to estimate the total heritability captured by common DNA markers on genotyping arrays. In the same sample of 3,154 pairs of 12-year-old twins, we directly compared twin-study heritability estimates for cognitive abilities (language, verbal, nonverbal, and general) with GCTA estimates captured by 1.7 million DNA markers. We found that DNA markers tagged by the array accounted for .66 of the estimated heritability, reaffirming that cognitive abilities are heritable. Larger sample sizes alone will be sufficient to identify many of the genetic variants that influence cognitive abilities.

Contra confused people on twitter and elsewhere, one need not speculate about what the BGI study will or will not find. The Visscher study convincingly demonstrated a year and a half ago that breeding values for IQ could be estimated from SNP microarray data. No new technology or theoretical breakthroughs are required to capture most of the genetic component of IQ -- only larger sample sizes.

In summary, GCTA estimates confirmed about two thirds of twin-study estimates of heritability for cognitive abilities, using the same measures at the same age in the same sample. This finding implies that, with sufficiently large sample sizes, many genes associated with cognitive abilities can be identified using the common SNPs on current DNA arrays. Whole-genome sequencing might help to close the rest of the missing-heritability gap by identifying rare DNA variants that contribute to the heritability of cognitive abilities, although other possibilities remain, including the possibility that twin and adoption studies have overestimated heritability. GCTA might also mark the beginning of the end of the nature-nurture controversy because it is much more difficult to dispute DNA-based evidence for genetic influence than it is to question the results of twin and adoption studies.

Bodily symmetry: origins and lifecourse associations with cognition, personality, and status

A 2012 PhD thesis (pdf):

Symmetry – measured as the size asymmetry of a group of symmetrical body traits such as ear height or elbow circumference – has often been used as an index of the capacity to develop normally despite stress and correlates with a wide range of outcomes including intelligence, health and aspects of behaviour. [. . .] The present work advances the existing empirical literature in six separate domains. It also improves upon past methodology by using novel methods of digital measurement of asymmetry as well as for the first time digitally measuring endogenous asymmetry as indexed by the bones and linking bone asymmetry to intelligence. The research was conducted on four samples. [. . .] Firstly, a sample of elderly participants from the Lothian Birth Cohort 1921 (LBC1921, n = 216) tested around ages 11, 79, 83, and 87. Secondly, the Science Festival Sample (SFS), a group of children recruited at a public science event aged between 4 and 15 (n = 856). Thirdly, a group of Orkney residents aged 18 to 86 (the ORCADES, n = 1200). Fourthly the Berlin Sample (BS), a group of Berlin residents (n = 207) between 20 and 30 years old. In the LBC 1921, men with poorer socioeconomic status in childhood had higher facial asymmetry in old age ( = -.25, p = .03). While investigating issues related to asymmetry in the same sample it was found that relatively more severe digit curvature – a minor physical anomaly – was associated with relatively greater cognitive decline ( = -.19, p = .02). Within the SFS asymmetry decreased across human childhood ( = -.16, p = .01), and more asymmetrical children exhibited slower choice reaction times ( = .0.17, p = .002). In the ORCADES sample, the more asymmetrical participants (as indexed by bone asymmetry) were less intelligent ( = -.24, p = .01). In the Berlin Sample and the LBC 1921 no consistent associations were found between personality traits and asymmetry. Collectively, these findings suggest symmetry functions as a measure of overall well-being as the trend is for higher asymmetry to be associated with a relatively poorer score on a variety of outcome measures. The findings considerably expand the number of existing studies in these empirical areas and in several cases – particularly asymmetry’s association with socioeconomic status in the elderly and reaction times among children – represent the first work on those areas. The present work confirms the finding that asymmetry is linked to adverse outcomes. However, the underlying mechanisms by which symmetry is linked to such outcomes remain underexplored and require clarification.

Unrelated articles on Harvard meritocrats

Financial Advisor: Harvard Tops In UHNW Alumni

Harvard University has turned out more graduates who have reached ultra-high-net-worth status than any other university in the world, according to Wealth-X, the educational and research business development organization of ultra-high-net-worth (UHNW) individuals.

Wealth-X defines this demographic as those with $30 million or more in assets. All but three of the universities with the highest number of UHNW individuals are in the United States.

Harvard has the highest number of billionaires with 52 and the largest number of UHNW individuals with 2,964. That group has $622 billion in net worth. The University of Pennsylvania, which has 1,502 UHNW graduates with a total of $242 billion in assets, is a distant second in aggregate UHNW assets. [. . .]

“American universities dominate the rankings largely because these prestigious institutions have been able to attract global talent,” says Wealth-X President David S. Friedman. “Most of the ultra-high-net-worth alumni have self-made fortunes, underscoring how these institutions have served as launching pads for many of the world’s most successful entrepreneurs and companies.”

The Fall of Academics at Harvard

This prevalence of academic dishonesty is symptomatic of a pervading mentality on campus that neglects the classroom. [. . .]

“Nowadays there’s much less willingness on the part of the students to take courses or to have majors for which they don’t see the utilitarian application,” he says. Students take less time to explore intellectually, worried more about carving out a tangible path for their futures.

Gardner cites the extensive recruitment for investment banking, management, and consulting firms as potentially adding fuel to the fire. This emphasis on what he calls a “one-way race to Wall Street, Silicon Valley, or Hollywood” comes with an “inordinate” worry about maintaining near-perfect grades—the only foreseeable path to weighty titles and even heavier paychecks.

When an education holds less value than the prestige that follows, dishonesty can be more easily justified as a means to an end. Harvard becomes simply a pit-stop on the way.

Along with these new definitions of success comes its reckless pursuit, by which, Gardner believes, students have become “hollow” in an ethical sense that plays out in an educational setting: They are not only more inclined to cheat, but are also more likely to see it as acceptable. He cites the example of Marilee Jones, former Dean of Admissions at MIT, who resigned in 2007 after admitting that she had lied on her own resume regarding her education. In a group of 15 students from another school to which Gardner spoke, none thought she should have been fired. Jones, they said, had been doing a good job—and everyone lies on their resume, after all.

The Harvard People I Know Who Are Breaking The Law (Again)

The first name of one of my freshman-year roomates was Nathan. Nathan's last name was Blecharczyk. Nathan is now the Chief Technology Officer of Airbnb, Inc., a company that raised $112 million from Andreesen-Horowitz, a prominent venture capital firm, and was recently valued at over $1 billion. Just after the company announced this enormous round of funding in mid-2011, news broke that Airbnb had been sending fraudulent, misleading e-mail spam via Craigslist, in violation of the CAN-SPAM Act, to thousands of individuals, and possibly many more. The company effectively denied responsibility, blaming a contractor. Nonetheless, the press releases from Andreesen-Horowitz citing Airbnb's amazing traffic already sounded suspect. Gawker's Ryan Tate asked, "Did Airbnb Scam Its Way To $1 Billion?", as did other major news publications.

The answer is most likely yes. What most people don't know is that during our freshman and sophomore years of college, Nathan was one of the top 100 spammers in the world. This key fact, which I'm guessing was not disclosed to Airbnb's investors, does not appear on Google or any major search engine because of ROKSO's good behavior de-listing policy, but if you know where to look, it's crystal clear. While we were roommates, Nathan ran a sort of enterprise called Data Miners out of Grays M-54 in Harvard Yard using a variety of aliases for himself. Data Miners would hop from service provider to service provider each week, sending millions of messages at a time. Nathan was clearly brilliant—he had designed both custom hardware and software to send these messages in bulk as efficiently as possible—and he paid his way through college thanks to these endeavors, but what he possessed in engineering skill he obviously lacked in morals. [. . .]

Airbnb isn't the only darling of Silicon Valley violating state money transmission law, however. If you've ever played Farmville, you know how tempting it is to buy items that will keep your farm going strong. Facebook has recently decreed that all games must use its Facebook Credits system, which allows customers to—you guessed it—pre-fund accounts that are denominated in credits, rather than dollars, so that those funds can be distributed to companies other than Facebook. Those accounts can be used now at third-party web sites (including international sites) and have long been used to compensate third-party game developers, who presumably convert the credits back into dollars on their end. This, too, is money transmission. Like Airbnb, Facebook doesn't have a license, and that's a shame, because Mark Zuckerberg, his directors, and investors could all find themselves in federal prison for violating forty-seven money transmission statutes, including California's.

However unlikely—and to be clear, it's "unlikely" because no State would bother prosecuting wealthy campaign donors and job providers, so for both companies the licenses are effectively optional, leaving your money at risk—this fate would be fitting given Mark's actions around the same time that Nathan was considering what to do about the FTC. As I've noted in the past, the scene that you didn't see in The Social Network was the one where he broke into Crimson reporters' e-mail accounts using failed Facebook sign in attempts, in violation of 18 U.S.C. § 1030, the Computer Fraud and Abuse Act, and common sense.

Misc. links

Genetic Genealogy Comes of Age: Perspectives on the Use of Deep-Rooted Pedigrees in Human Population Genetics

Facial Structure Is Indicative of Explicit Support for Prejudicial Beliefs

Our results indicate that males with a greater fWHR are more likely to explicitly endorse racially prejudicial beliefs, though fWHR was unrelated to implicit bias. NN

"Ironically" (according to Vice blogger) a Man's Face Can Tell You If He's Likely to Act Racist

There’s an obvious irony to a study that says we can tell if a man will act bigoted based on the shape of his face. But the logic underpinning the study, conducted by researchers at the University of Delaware and soon to be published in the journal Psychological Science, is a circuitous and unexpected one, and makes a persuasive case.

Turns out it’s all about the testosterone.

Recent research indicates that men with high levels of testosterone have certain facial characteristics that set them apart from men with less testosterone. In particular, they have what researchers call a higher facial Width-to-Height Ratio (fWHR) which compares the distance between cheekbones to the distance between the upper lip and midbrow.

Charlton: Modern sub-fertility may be a pathologically slow life history, triggered by a supernormal stimulus of modernity

The Human Varieties Global IQ Dataset / HVGIQ

Human Varieties: Colorism in America?

Light skin color does not seem to cause higher IQ or educational achievement either through pleiotropy or because of color discrimination — otherwise the within-families correlations would have been similar to those obtained between families. Colorism, the theory that discrimination based on skin color is a major source of socioeconomic differences, appears to not apply within the African American population, at least as far as IQ and educational attainment are concerned.

Genetic Influences on the Overlap Between Low IQ and Antisocial Behavior in Young Children

The well-documented relation between the phenotypes of low IQ and childhood antisocial behavior could be explained by either common genetic influences or environmental influences. These competing explanations were examined through use of the Environmental Risk Longitudinal Twin Study 1994–1995 cohort (Moffitt & the E-Risk Study Team, 2002) of 1,116 twin pairs and their families. Children’s IQ was assessed via individual testing at age 5 years. Mothers and teachers reported on children’s antisocial behavior at ages 5 and 7 years. Low IQ was related to antisocial behavior at age 5 years and predicted relatively higher antisocial behavior scores at age 7 years when antisocial behavior at age 5 years was controlled. This association was significantly stronger among boys than among girls. Genetic influences common to both phenotypes explained 100% of the low IQ–antisocial behavior relation in boys. Findings suggest that specific candidate genes and neurobiological processes should be tested in relation to both phenotypes.

Toxoplasma gondii infection enhances testicular steroidogenesis in rats (pdf)

The genetic origin and history of speed in the Thoroughbred racehorse and a related talk

Selective breeding for speed in the racehorse has resulted in an unusually high frequency of the C-variant (g.66493737C/T) at the myostatin gene (MSTN) in cohorts of the Thoroughbred horse population that are best suited to sprint racing. Here we show using a combination of molecular- and pedigree-based approaches in 593 horses from 22 Eurasian and North-American horse populations, museum specimens from 12 historically important Thoroughbred stallions (b.1764-1930), 330 elite-performing modern Thoroughbreds and 42 samples from three other equid species that the T-allele was ancestral and there was a single introduction of the C-allele at the foundation stages of the Thoroughbred from a British-native mare. Furthermore, we show that although the C-allele was rare among the celebrated racehorses of the 18th and 19th centuries, it has proliferated recently in the population via the stallion Nearctic (b.1954), the sire of the most influential stallion of modern time, Northern Dancer (b.1961).

Alistair Overeem's testosterone level at dangerously low levels in Antonio Silva fight

Overeem's test, taken the morning after the fight, was low enough that most doctors would recommend him to be on a testosterone replacement plan even if he was not an athlete [. . .]

Overeem went from being a 205-pound light heavyweight who lost frequently, to looking like a different human being, gaining nearly 60 pounds of competitive weight with no increase in body fat. Due to that, he probably had more suspicion over steroids than nearly any MMA competitor, even before he tested positive the first time he was tested on a date he wasn't told about well in advance.

Save the Pygmies

Pygmy slavery is a wide range from being held to gunpoint by rebel militia's in the gold, diamond, and coltan mines to being slaves because of no possibility of monetary gain or obtaining land ownership. The Pygmies that we have been seeing released are not being held to gunpoint or in shackles. The kind of slavery we are immediately putting an end to is slavery due to having no other option to survive. The easiest way to end this kind of slavery has been to see them be placed on their own land, and then showing them how to work it for themselves instead of their slavemasters. This year in Congo will give more insight into all the unique kinds of slavery and what action can be taken for the Pygmies of Africa (Meaning a future goal to expand into other countries where the Pygmy people reside). The main reason for Pygmy slavery is due to extreme racism where surrounding tribes believe the Pygmy people are still in the transitional stage from monkey to human. This belief accounts for the hunting, killing, cooking, and cannibalism against the tribe as well as other atrocities against humanity in recent years.

Gene flow and the limits to natural selection

In general, individuals who survive to reproduce have genotypes that work relatively well under local conditions. Migrating or dispersing offspring elsewhere is likely to decrease an individual's or its offspring's fitness, not to mention the intrinsic costs and risks of dispersal. Gene flow into a population can counteract gene frequency changes because of selection, imposing a limit on local adaptation. In addition, the migrant flow tends to be higher from densely populated to sparsely populated areas. Thus, although the potential for adaptation might be greatest in poor and sparsely populated environments, gene flow will counteract selection more strongly in such populations. Recent papers, both theoretical and empirical, have clarified the important role of migration in evolution, affecting spatial patterns, species ranges and adaptation to the environment; in particular, by emphasizing the crucial interaction between evolutionary and demographic processes.

Keywords
local adaptation; gene swamping; migration rescue; migration meltdown; gene flow; natural selection