Since last December, there have been lots of COVID-19（新冠肺炎） cases both in and out of China. It's not the first time for humans to fight with Viruses. Viruses have brought big trouble to humans, because they may cause widespread disease and death.
What are they? Viruses are considered to be non-living organisms ( 有机物). They can infect animals, plants and humans, making them sick. They have materials like DNA and are protected by a kind of special skin.
Viruses can't reproduce( 繁殖) on their own. Instead, they break in the cells( 细胞) of living organisms to reproduce, spread and take over. But the basic question is, "Where did viruses first come from?" Until now, no clear explanation for this question. "It is difficult to find out where viruses first came from," Ed Rybicki, a virologist at the university of Cape Town in South Africa, told Scientific American, "because viruses don't leave fossils ( 化 石 ) and because it is difficult to study the ways they use to make copies of themselves within the cells they've broken in." Understanding where they came from means fully understanding the history of their hosts( 宿主) – not only humans, but also plants and other animals, which is a difficult task, saysNature.
UK physicist Isaac Newton once said, "Nature is pleased with simplicity and nature is no dummy (傻子)." Indeed, mother nature can provide almost everything humans need if we follow her rules. But if we break the rules, she is likely to be cruel and mad at us. It is believed that the outbreak of COVID-19 is a good example. Humans try to change mother nature. They use more land to make buildings, catch some wild animals to meet their own needs. Humans gradually throw our mother nature out of balance(平衡). For example, cutting a large number of forests leads to global(全球的) warming.
Although we don't know exactly what first caused the COVID-19 outbreak, Brian Lamacraft at Medium said it's time for people to "think carefully about our relationship with our mother nature" and "reconnect with this world and everything that we've been given". After all, according to US poet Gary Snyder, "Nature is not the place to visit. It's our home."
