In Sheep, an Upside To Immune Weakness

Due to the weakness of the immune system, animals are vulnerable to disease and parasites, but strangely, animals that seem to have significant drawbacks by natural selection are not always excluded .

This may be because the weakness brings some advantages. This research has been reported in the journal Science, and a strong immune system helps longevity of ewes but also decreases reproductive success rate.

Ecologist Andrea Graham and his colleagues at Princeton University studied the ancient varieties found in the Scottish archipelago of St Kilda, Soay sheep.

Because of the cold winter and harsh living environment, the last resident of St Kilda has left about 80 years ago. But they left their sheep, management and free roaming. Sheep are no longer selected by breeders, and now they are selected to form research groups that are naturally relatively accessible.

And I studied them. Every August, Dr. Graham et al. Calculated parasites and sampled sheep's feces to collect blood from sheep to measure antibody productivity.

They discovered that the average life expectancy of the 410 ewives studied was 6 years. Some people have lived for 15 years, and those who died at the age of 3 years or short-lived ewes have a lower antibody concentration than longevity ewes, so their lifespan is short. But why does natural selection not delete them?

Dr. Graham said the researchers found this to be a problem: "What do these sheep do with low antibody concentrations?"

She stated that the answer is that short-lived ewes are more likely to produce lamb. Those young people are almost twins, almost every year they copy. Longevity sheep do not breed every year

"This may be a matter of mere energy balance," Dr. Graham said. "The energy that produces antibodies may reduce the energy that produces the fetus."

In the sixteenth century explorers reported pasturelands of African nomads who had received similar genetic techniques to protect their sheep from rambp. The use of smallpox to immunize a human and sheep pox-immunized sheep resulted in solid immunity in both groups, but the post mortality rate after vaccination is a totally toxic disease contraction rather than an attenuated form It was high for. The era of contemporary immunization was born out of Edward Jenner who recognized that in 1796 humans could use vaccinia as a vaccination to prevent smallpox.

There is an American old story that father used to tell their boys once. The story explains three kinds of men: wolves, sheep and sheep dogs. Wolves are lonely and strong, they prey on sheep and weak wolves. Sheep was innocent and was eaten by a wolf. Shepherds are strong and reliable, they protect sheep from wolves. As a father, I want to make my son a shepherd. Among my family, I am responsible for the role of a father Masculinity is the source of pride and identity, and also the goal of desire. As a man, I am not good at everyday life and schedule planning, and when I'm old and torn, I will apply socks and patches. However, the following maxims have no room for negotiation. A simple version that we crave is like this:

Collective immunization protects the community from infectious diseases by mass vaccination of people with these diseases so that cattle and sheep groups use pure figures to protect their members from predators. The more members of the "group" who are immune to disease, the more they can protect the entire population from the occurrence of disease. Individuals can develop immunity against infectious diseases in two ways: the infection can cause the pathogen or is vaccinated. Because the vaccine can induce immunity without causing disease, it is a relatively safe and effective way to fill communities with anti-patients. Individuals receiving these vaccinations will protect themselves from illness. But this time, we will protect community members who can not receive vaccinations, prevent disease chains from reaching them, and limit potential outbreaks.