The eye color is not the result of a particular pigment but rather the relative absence of higher concentrations of melanin to make them brown. This led to the emergence of other colors such as blue, green, and hazel eyes. Originally, human eyes were brown, but around 6,000 to 10,000 years ago a genetic mutation slipped in which turned off the ability to produce enough melanin to sustain this color in some people. But before we try to squish aliens into this explanatory gap, there are some simpler, albeit less sensational, explanations worth considering first, and they all have to do with genes, which are prone to mutating naturally.Ī good example here is eye color. As mentioned above, Rh-negative blood is quite rare – around 15 percent of Caucasians are negative, while only 8 percent of Black people and only 1 percent of Asians are. So if not aliens, where does Rh-negative blood come from?Īt the moment, there is no clear consensus on why some people are Rh-positive and others are not. In reality, the baby has different DNA from its mother, which leads to complications during pregnancy. It is possible this seemingly weird phenomenon is what has caused the alien explanation to appear so compelling as, on the surface at least, it looks like the mother is rejecting the baby, as if they were from two different species. In this case, the mother’s antibodies will attack the child’s blood. The Rh blood group can play an important role in fatal blood diseases, especially erythroblastosis fetalis, which can develop in fetuses and newborns if an Rh-negative mother gives birth to an Rh-positive child. Some have also claimed that Rh-negative people have higher IQs, are more sensitive to the environment, and may have lower body temperature and blood pressure, among other things, but this is far from universally accepted. There does not appear to be any other significant differences resulting from the blood type, though some have hypothesized that it may affect resistance to certain parasites, especially the one that causes toxoplasmosis. In essence, the discovery meant that blood types can be characterized as either Rh-positive or Rh-negative, a factor that doubled the number of known blood types from four (A, B, AB, and O) to eight.įor most people, whether they are Rh-negative or positive will not be a concern unless they require a blood transfusion. Through their experiments, the two scientists identified a new antigen on the surface of red blood cells which they named the Rhesus factor (or Rh factor) after the Rhesus macaques used in the experiments. They were trying to figure out why some people experienced adverse reactions when receiving blood from certain donors. But then in 1937, he and Wiener turned their attention to a perplexing issue related to blood transfusions. In the early 20 th century, Landsteiner had also made important contributions to our understanding of blood types as he identified the ABO system. Karl Landsteiner and Alexander Wiener played the most significant role in identifying the Rhesus blood type. The effect makes it look like the viewer is watching a discussion of equally valid perspectives. In this instance, a professor of Anthropology provides a brief overview of the science behind rhesus-negative blood but is then sidelined by authors of alien-related ideas who add their own spin to the discussion without challenge. This involves meshing the views of scientists and other experts with non-experts in a way that makes them look like they are all contributing to the same conversation. Although this claim lacks any actual evidence, it is presented as an intriguing possibility through a typical rhetorical sleight of hand.
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