Canada is dealing with a series of intense wildfires that have spread from the western provinces to Quebec, with hundreds of forest fires burning. Wind has carried smoke from the fires southward, triggering air quality alerts throughout the United States. The U.S. Environmental Protection Agency Tuesday issued a poor air quality alert for New England, a day after parts of Illinois, Wisconsin and Minnesota received a similar advisory. Last week, U.S. officials as far south as Maryland, Baltimore, Virginia and Pennsylvania reported being impacted by the wildfires. Fine-particle pollution — known as “PM 2.5” — is what’s being measured. The tiny particles are small enough to get past airway defenses and cause breathing problems.

Scientists say they've found evidence an ancient human cousin may have buried its dead and carved symbols into cave walls, surprising findings for a creature with a small brain. Fossil remains of the species were uncovered in underground caves in South Africa around a decade ago. Since then, researchers have kept squeezing into the caves to look for clues. Now, researchers say the burials and carvings show that the species called Homo naledi was capable of more complex behavior than expected, since its brain was only about one-third the size of ours. Their findings were posted online Monday but some outside scientists think more evidence is needed.

Scientists have found that air quality monitoring stations pick up lots of DNA that can reveal what plants and animals have been in the area.. Researchers reported Monday that air monitoring stations set up to test for pollution also suck up DNA from the local environment. They say this could be a useful way to see how biodiversity changes over time. After testing air filters from stations in the UK, the scientists were able to identify more than 180 kinds of plants, animals and fungi in the area. The filters picked up on species like hedgehogs, deer and owls that shed their DNA into the atmosphere.

The cause of global warming is showing no signs of slowing as heat-trapping carbon dioxide in Earth’s atmosphere has increased to record highs in its annual Spring peak. The National Oceanic and Atmospheric Administrations says carbon dioxide levels in the air are jumping at one of the fastest rates on record. Those levels are now the highest they’ve been in more than 4 million years. The last time the air had similar amounts was during a less hospitable hothouse Earth before human civilization. Levels for May, which is when carbon dioxide most saturates the air before plants suck it up, are at 424 parts per million.