Forensic DNA testing has become crucial in criminal investigations and legal proceedings. DNA has linked people to crime scenes using hair or blood and exonerated wrongfully convicted individuals. This type of DNA is called environmental DNA (eDNA) because it is collected from the environment, rather than from a person. Scientists have also begun analyzing eDNA from non-human organisms. All organisms are constantly shedding bits of themselves into the environment, and the DNA extracted from these materials is helping scientists identify organisms that live or lived in an environment even if the organism itself cannot be seen. eDNA technology is advancing public health surveillance and environmental conservation by allowing scientists to gather much more information about our surroundings.

SARS-CoV-2 may have spread to humans from an animal host, but it is not the only disease-causing agent (i.e. pathogen) to have done so. Lyme disease, Ebola virus, influenza, HIV, the plague, and rabies virus are just some examples of zoonotic diseases, meaning that they originated in animals and spread (i.e spilled over) to humans.

In the last few years, we have witnessed a significant increase in weather-related disasters throughout the world. Droughts, wildfires, heat waves, hurricanes, and floods have all become more extreme. These are largely driven by increases in global temperature, which is caused by the huge amount of carbon dioxide (CO₂) that humans have released into the atmosphere.

In a 2002 essay, Dutch atmospheric chemist Paul Crutzen popularized the name “Anthropocene” for the current geologic time period. Though unofficial, it is widely accepted by scientists because of how drastically humans have altered the Earth. We have cleared forests, built cities, diverted waterways, replaced wild animals with domestic ones, created billions of tons of plastic waste, and perhaps most significantly, changed the climate.

When we think of viruses today, we imagine tiny disease-causing invaders. The COVID-19 pandemic has brought viruses to the forefront of people’s minds, and we are constantly looking for ways to avoid, kill, and fight off viruses. Many well-known viruses do cause diseases in animals and plants, but a far greater number of viruses are necessary for the survival of cellular life, either for an individual species or an entire ecosystem. Viruses help maintain the health of the oceans, and still others can help our immune systems develop.

The 2010 death of trainer Dawn Brancheau at SeaWorld Orlando came as a shock to the world. Brancheau was an experienced trainer who had worked with orcas for 15 years. The day of her death, she was performing a show with Tilikum, a large male killer whale, who drowned her. According to SeaWorld executives, orcas and other performing animals, such as dolphins and sea lions, live good lives in captivity with medical care and loving trainers. They claimed that the death of Dawn Brancheau was a random accident due to trainer error.