Power of Prediction One of the valuable attribute of a good hypothesis is to predict for future.
Hypothesis9 1: Evidence from studies of nuclear and mitochondrial DNA extracted from Neanderthal fossils and humans points to fascinating hypotheses concerning the types of interbreeding that occurred between these two species. Humans and Neanderthals share a small percentage of nuclear DNA.
However, humans and Neanderthals do not possess the same mitochondrial DNA. In mammals, mitochondrial DNA is exclusively maternally inherited. Taking into account an understanding of interspecific hybridity, the available data leads to the hypothesis that only male Neanderthals were able to mate with female humans.
Interbreeding between male Neanderthals and female humans, as the only possible scenario, accounts for the presence of Neanderthal nuclear DNA, the scarcity of Neanderthal Y-linked genes, and the lack of mitochondrial DNA in modern human populations.
Introduction Since the discovery of the first recognized Neanderthal remains inscientists have debated about the relationship between Neanderthals and humans. Neanderthals were not as tall as humans, had shorter limbs, thicker bones, a protruding mid-face, pronounced brow ridges, a receding chin, a morphologically different vocal tract, and a raised larynx.
Over time, Neanderthals genetically diverged. Analyses of mitochondrial DNA mtDNA sequences extracted from Neanderthal fossils suggest that their most recent common ancestry dates back to approximatelyyears ago 2. Neanderthals inhabited a vast geographical area extending from Portugal to western Siberia and from northern Europe to the Middle East until approximately 25, years Characteristics of a hypothesis 3.
Recent evidence from DNA extracted from fossil Neanderthal bones reveals geneflow between Neanderthals and anatomically modern humans in the Middle East around 80, to 50, years ago as humans spread out of Africa and into Europe and Asia 4.
Despite morphological and ontogenetic differences to humansit appears that Neanderthals did not become extinct without first contributing some of their nuclear DNA to the human gene pool.
Indeed, there was chronological overlap and coexistence between Neanderthals and humans 9,10and hybrid specimens have been found that feature both Neanderthal and modern human features It appears that many centuries of hybridization led to mosaic fossils with human cranial and dental features mixed with Neanderthal body proportions.
Studies of nuclear DNA and hybrid fossils offer convincing evidence for interbreeding between Neanderthals and humans, but with a twist. Mitochondria are tiny energy regulating organelles that reproduce asexually and live inside each cell of our bodies.
In mammals, mitochondria are exclusively maternally inherited This intriguing mix of findings leads us to contemplate the types of interbreeding that occurred between Neanderthals and humans.
Understanding Interspecific Hybridity Speciation is the process by which new species are formed. If, for example, a species is subdivided into two subpopulations that become geographically separated, then the two groups may accumulate biological differences that reduce hybrid fertility.
A clear speciation event between Neanderthals and humans has not been documented to date, but Neanderthals seem to have accrued distinctive characteristics and features along the second half of the Middle Pleistocene Researchers have long wondered if Neanderthals were an entirely separate species.
Recent DNA evidence 4 might suggest that they were not. However, even if Neanderthals were a separate species, speciation without loss of hybrid fertility is possible.
Take the example of the Camelidae that originated in Florida. The little ones migrated into South America and into the Andes to become the Llama, Alpaca, Vicuna and Guanaco— phenotypically quite different species, but all of which will produce fertile hybrids when crossbred.
The bigger ones migrated up the Rockies, across the Bering Strait, through Mongolia and Northern China—where we find the two-humped Bactrian camel— and into India and from there into Persia and Saudi Arabia—where we find the one-humped Dromedary camel.
The spread of the Camelidae from the Americas to the Middle East is an example of phenotypic differentiation in a sexually reproducing species as a result of geographical isolation. Researchers have been able to produce Camas by inseminating female Alpacas with Dromedary semen, although the reciprocal cross gave fetuses, but no live-born young 24, As Old World and New World Camelids are some 10 — 12 million years apart, we can be fairly certain, through inference, that Neanderthals were able to hybridize with humans from whom they had diverged by only a few hundred thousand years.
Given that mtDNA is exclusively maternally inherited in mammals, the absence of Neanderthal mtDNA in modern humans suggests that perhaps only male Neanderthals and female humans were able to produce fertile offspring. Possible outcomes of Neanderthal-Human Interbreeding. Mammals contain two different types of DNA: Nuclear DNA from Neanderthals has been found in the human genome.
Mitochondrial DNA from Neanderthals has not been found in humans. While not conclusive, these findings could indicate that male Neanderthals were able to reproduce with female humans, but that the reciprocal cross was absent, rare or sterile.
Considering that Neanderthals were robust and humans were in comparison gracile, male Nean-derthals may have had le droit de seigneur in any matings. In mammals, the heterogametic sex is the male sex with two different sex chromosomes, X and Y.In probability theory and statistics, a unit root is a feature of some stochastic processes (such as random walks) that can cause problems in statistical inference involving time series models.A linear stochastic process has a unit root if 1 is a root of the process's characteristic kaja-net.com a process is non-stationary but does not always have a trend.
In describing the conceptual basis of a stress intervention method, Emotional Brain Training (EBT), a program which integrates advances in neuroscience and stress physiology, we propose a .
The MendelWeb Glossary. This is a glossary of terms that appear in Mendel's paper and other areas of MendelWeb. It is not meant to be exhaustive, and is aimed primarily at students in secondary and undergraduate schools. The aquatic ape hypothesis (AAH), also referred to as aquatic ape theory (AAT) and more recently the waterside model, is the idea that the ancestors of modern humans were more aquatic and as such were habitual waders, swimmers and divers.
The hypothesis in its present form was proposed by the marine biologist Alister Hardy in , who argued that a branch of apes was forced by competition. Habitat Location where a plant or animal lives. Hadean Geologic eon that occurred from to million years ago. The Earth's oldest rocks date to the end of this time period.
Hadley Cell Three-dimensional atmospheric circulation cell located at roughly 0 to 30° North and South of the equator. Board of Directors.
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