Evolution has influenced every organism since the beginning of life, and humans are no exception to that. Throughout time, it has been claimed that humans are the ultimate being, better than all others. Now, it is common knowledge that is not true, but some still think that humans are done evolving, some think this due to modern medicine while others believe that it is due to the fact that we cannot improve. This notion that humans are done evolving is false, human kind is still evolving, in many ways. Culture has in many ways shaped humans, one very successful way is lactose tolerance as only 5% of those with Western European descent are lactose intolerant, but areas where cattle herding was not popular such as Asia, nearly 90% are lactose intolerant. In developing countries, disease resistance as well as physical fitness in poverty stricken areas cause selective pressures that influence evolution in those areas. In developed countries, fertility is one of the main ways that evolution is in action. The purpose of this paper is to review current literature in order to demonstrate that evolution has not stopped due to modern medicine; in fact, many selective pressures are very prevalent today.
In developing countries many live without access to adequate healthcare including preventative care and immunizations. Typically, in the poverty stricken parts of these countries, people live on very little care at all. Selective pressures are in action as those who have resistance to those diseases as well as those who are more physically fit are more likely to reproduce, and have more offspring. Western countries have been able to provide immensely for their people, but not every place in the world is like that “The majority of the world's population does not live in Western affluence. Much of it lives in conditions of great poverty, in which malnutrition, infectious disease and acute injury (from causes ranging from personal brutality to war) are the major causes of death (Baines, 2009)”. These factors all are selective pressures acting upon the people. In order to reproduce in such a poverty stricken area, one’s body must adapt to the conditions or there is no way that a fetus would be able to develop without dying before leaving the womb. Although features of poverty exert selective pressure, diseases are one of the most prevalent sources of selective pressure upon populations that lack adequate healthcare. “Indeed, researchers are now tracking how deadly maladies such as AIDS and malaria exert selective pressure on people today (Balter, 2005)” says Sarah Tishkoff, a geneticist at the University of Maryland. This research will be able to see at what extent selective pressures are influencing the people of these countries. This will prove that natural selection is happening every day, indeed “people are dying daily [of infectious disease], and those who have genotypes that confer some resistance are going to have more offspring. That is natural selection in action (Balter, 2005)”. Each time a person dies from an infectious disease, especially before they have reached an age of maturity, they have done their part for natural selection. Because they have not been able to have children yet, they will not pass their genes on. Although some think that disease resistance is what creates the selective pressures that act on evolution, there are other that think it is just physical fitness and having an adaptable body “Most resistance to infectious disease is the result of overall health and the “adaptive” immune system, which, rather than being specifically armed against pathogens in advance, detects invading pathogens and then evolves antibodies against them (Weiss, 2015)”. Although this isn’t as direct of a selective pressure as immunity to the disease, this is still a factor that will cause some to have more offspring than others, because their body is more adapt to the environment they live in. People in developing countries without access to good healthcare and those who live in poverty are subject to selective pressure due to fitness or immunity to diseases.
Evolution is still prevalent in all countries, even those that are developed. Selective pressures such as fertility and reproductive fitness show how selection still takes place in countries without disease epidemics. Although it may seem that the lack of prevalence of certain infectious diseases in developed countries would lead to an absence of evolution in those areas, the entire idea of that is false. As said by Mary Pavelka, “The very notion that … we might not be evolving derives from a belief that all other life forms were merely stages on the way to the appearance of humans as the intended end point,”(Balter,2005). It is well known that evolution does not lead to a singular master species, as it was once hypothesized, but instead evolution works in a way to specialize a species to its niche in the environment. Although selective pressure in developed countries does not typically come as a result of disease, there are other pressures that cause selection to occur “selection is happening on at least three levels: preproductive mortality, reproductive dynamics and reproductive success” (Baines,2009). Fertility also happens to be a key player in evolution in developed countries. While there are mothers able to reproduce despite the fact that they are unable to themselves with surrogates, this is still an uncommon practice and many women unable to conceive themselves will adopt, or even use someone else’s egg. Similarly, to women not passing their genes on when unable to reproduce, sperm donors are becoming increasingly popular, meaning that many men unable to reproduce easily will not have their genes passed down to their offspring and will instead raise a child who has a higher chance of reproducing. “Even in developed countries, where survival tends to be prolonged for almost all, recent studies suggest that there are still genetic differences among people in fertility and reproductive fitness, an indication that natural selection is operating.” (Balter, 2005). Immunizations, awareness, and increased preventative measures of infectious diseases in developed countries causes less selective pressures on those who aren’t immune to them, but there are still selective pressures that causes certain genes to continue on in higher numbers than others.
Evolution has been at work since the beginning of life, but it is only since the dawn of humans that so many factors influencing evolution have starting fluctuating due primarily to culture. Cigarettes are something that the older generation still remembers being encouraged by doctors to use, and now it is the complete opposite. This cultural change had made an impact on the genes of many in the younger generations, just “in the last generation the effect of a gene that favors cigarette smoking has dwindled in some groups. (Pennisi, 2016)” Although current generations have been the current focus so far, going back a few generations can show how evolution has shaped through culture in the past century and gives evidence of very recent evolution. One research team did testing on genes and took note of the number of singletons, or single unique mutations near the allele. It was said that the less singletons there were near an allele the faster it has spread thus meaning it has become more prevalent. This research was focused on the previous 100 generations or 2,000 years, this research found found fewer singletons near alleles for blond hair and blue eyes, indicating that these traits, too, have rapidly spread over the past 2000 years” (Pennisi, 2016). This research based in England hypothesized this due to genes for lighter hair causing lighter skin making the body able to produce more vitamin D in times of low sunlight, or simply just sexual selection due to the population wanting blonde partners. Domestication of animals and the beginning of farming for the population has also greatly influenced selective pressures. Indeed, “among populations with a long history of cattle herding and milk consumption, the ability to metabolize lactose is maintained into adulthood. These are clear examples that natural selection has recently acted upon our species (Stock, 2008)”. This cultural difference can be seen as nearly 65% of the world’s population is lactose intolerant, but only 5% of those with northern European decent are lactose intolerant (Itan et al., 2010). This proves that the culture of farming cattle in the area has put selective pressure on those that were unable to drink milk causing them to reproduce less. Cultural differences are causing a slow in selective pressures societal norms now, that were once a large part of choosing a mate. Education is included with the many things that are now considered a right that was once a privilege, “Consistent with the results from previous studies with phenotypic data…natural selection has been operating slowly relative to the rapid changes that have occurred over the past few generations, presumably due to cultural and environmental factors. For instance, my estimate of a directional selection differential of EA of about −1.5 mo. of education per generation pales in comparison with the…native-born Americans born between 1876 and 1951… about 2 y of education per generation (Beauchamp, 2016)”.
Evolution has influenced every organism since the beginning of life, and humans are no exception to that. Throughout time, it has been claimed that humans are the ultimate being, better than all others. Now, it is common knowledge that is not true, but some still think that humans are done evolving, some think this due to modern medicine while others believe that it is due to the fact that we cannot improve. This notion that humans are done evolving is false, human kind is still evolving, in many ways. Culture has in many ways shaped humans, one very successful way is lactose tolerance as only 5% of those with Western European descent are lactose intolerant, but areas where cattle herding was not popular such as Asia, nearly 90% are lactose intolerant. In developing countries, disease resistance as well as physical fitness in poverty stricken areas cause selective pressures that influence evolution in those areas. In developed countries, fertility is one of the main ways that evolution is in action. The purpose of this paper is to review current literature in order to demonstrate that evolution has not stopped due to modern medicine; in fact, many selective pressures are very prevalent today.
In developing countries many live without access to adequate healthcare including preventative care and immunizations. Typically, in the poverty stricken parts of these countries, people live on very little care at all. Selective pressures are in action as those who have resistance to those diseases as well as those who are more physically fit are more likely to reproduce, and have more offspring. Western countries have been able to provide immensely for their people, but not every place in the world is like that “The majority of the world's population does not live in Western affluence. Much of it lives in conditions of great poverty, in which malnutrition, infectious disease and acute injury (from causes ranging from personal brutality to war) are the major causes of death (Baines, 2009)”. These factors all are selective pressures acting upon the people. In order to reproduce in such a poverty stricken area, one’s body must adapt to the conditions or there is no way that a fetus would be able to develop without dying before leaving the womb. Although features of poverty exert selective pressure, diseases are one of the most prevalent sources of selective pressure upon populations that lack adequate healthcare. “Indeed, researchers are now tracking how deadly maladies such as AIDS and malaria exert selective pressure on people today (Balter, 2005)” says Sarah Tishkoff, a geneticist at the University of Maryland. This research will be able to see at what extent selective pressures are influencing the people of these countries. This will prove that natural selection is happening every day, indeed “people are dying daily [of infectious disease], and those who have genotypes that confer some resistance are going to have more offspring. That is natural selection in action (Balter, 2005)”. Each time a person dies from an infectious disease, especially before they have reached an age of maturity, they have done their part for natural selection. Because they have not been able to have children yet, they will not pass their genes on. Although some think that disease resistance is what creates the selective pressures that act on evolution, there are other that think it is just physical fitness and having an adaptable body “Most resistance to infectious disease is the result of overall health and the “adaptive” immune system, which, rather than being specifically armed against pathogens in advance, detects invading pathogens and then evolves antibodies against them (Weiss, 2015)”. Although this isn’t as direct of a selective pressure as immunity to the disease, this is still a factor that will cause some to have more offspring than others, because their body is more adapt to the environment they live in. People in developing countries without access to good healthcare and those who live in poverty are subject to selective pressure due to fitness or immunity to diseases.
Evolution is still prevalent in all countries, even those that are developed. Selective pressures such as fertility and reproductive fitness show how selection still takes place in countries without disease epidemics. Although it may seem that the lack of prevalence of certain infectious diseases in developed countries would lead to an absence of evolution in those areas, the entire idea of that is false. As said by Mary Pavelka, “The very notion that … we might not be evolving derives from a belief that all other life forms were merely stages on the way to the appearance of humans as the intended end point,”(Balter,2005). It is well known that evolution does not lead to a singular master species, as it was once hypothesized, but instead evolution works in a way to specialize a species to its niche in the environment. Although selective pressure in developed countries does not typically come as a result of disease, there are other pressures that cause selection to occur “selection is happening on at least three levels: preproductive mortality, reproductive dynamics and reproductive success” (Baines,2009). Fertility also happens to be a key player in evolution in developed countries. While there are mothers able to reproduce despite the fact that they are unable to themselves with surrogates, this is still an uncommon practice and many women unable to conceive themselves will adopt, or even use someone else’s egg. Similarly, to women not passing their genes on when unable to reproduce, sperm donors are becoming increasingly popular, meaning that many men unable to reproduce easily will not have their genes passed down to their offspring and will instead raise a child who has a higher chance of reproducing. “Even in developed countries, where survival tends to be prolonged for almost all, recent studies suggest that there are still genetic differences among people in fertility and reproductive fitness, an indication that natural selection is operating.” (Balter, 2005). Immunizations, awareness, and increased preventative measures of infectious diseases in developed countries causes less selective pressures on those who aren’t immune to them, but there are still selective pressures that causes certain genes to continue on in higher numbers than others.
Evolution has been at work since the beginning of life, but it is only since the dawn of humans that so many factors influencing evolution have starting fluctuating due primarily to culture. Cigarettes are something that the older generation still remembers being encouraged by doctors to use, and now it is the complete opposite. This cultural change had made an impact on the genes of many in the younger generations, just “in the last generation the effect of a gene that favors cigarette smoking has dwindled in some groups. (Pennisi, 2016)” Although current generations have been the current focus so far, going back a few generations can show how evolution has shaped through culture in the past century and gives evidence of very recent evolution. One research team did testing on genes and took note of the number of singletons, or single unique mutations near the allele. It was said that the less singletons there were near an allele the faster it has spread thus meaning it has become more prevalent. This research was focused on the previous 100 generations or 2,000 years, this research found found fewer singletons near alleles for blond hair and blue eyes, indicating that these traits, too, have rapidly spread over the past 2000 years” (Pennisi, 2016). This research based in England hypothesized this due to genes for lighter hair causing lighter skin making the body able to produce more vitamin D in times of low sunlight, or simply just sexual selection due to the population wanting blonde partners. Domestication of animals and the beginning of farming for the population has also greatly influenced selective pressures. Indeed, “among populations with a long history of cattle herding and milk consumption, the ability to metabolize lactose is maintained into adulthood. These are clear examples that natural selection has recently acted upon our species (Stock, 2008)”. This cultural difference can be seen as nearly 65% of the world’s population is lactose intolerant, but only 5% of those with northern European decent are lactose intolerant (Itan et al., 2010). This proves that the culture of farming cattle in the area has put selective pressure on those that were unable to drink milk causing them to reproduce less. Cultural differences are causing a slow in selective pressures societal norms now, that were once a large part of choosing a mate. Education is included with the many things that are now considered a right that was once a privilege, “Consistent with the results from previous studies with phenotypic data…natural selection has been operating slowly relative to the rapid changes that have occurred over the past few generations, presumably due to cultural and environmental factors. For instance, my estimate of a directional selection differential of EA of about −1.5 mo. of education per generation pales in comparison with the…native-born Americans born between 1876 and 1951… about 2 y of education per generation (Beauchamp, 2016)”.