The lack of clues left behind by ancient Americans has made it difficult for researchers to pinpoint precisely when humans first arrived on the continent. However, it has always been believed to be about 13,000 years ago, just as the world was thawing from the last ice age. Now, evidence from the Chiquihuite Cave in Zacatecas, Central Mexico, seems to suggest that prehistoric humans may have been living in North America as early as 30,000 years ago.

Male birds typically sing the same tunes as the rest of their species because an unrecognizable song defeats the two primary reasons for their crooning — to establish and defend their territory and to attract mates. While the songs, which are passed down from generation to generation, may vary slightly by region, any new compositions are typically limited to the local environment. However, for reasons unknown to scientists, white-throated sparrows across Canada are abandoning their classic song for a catchy new tune "written" by their peers in British Columbia.

Scattered across the ocean bed, and often hidden from the human eye, are hundreds, or perhaps even thousands, of "blue holes." The massive underwater sinkholes, which host a diverse biological community — ranging from coral to sponges to sharks to sea turtles — were formed thousands of years ago when groundwater dissolved karst, a type of porous limestone rock found on ocean floors.

American civil rights leader and U.S. Representative John Lewis (D-GA) passed away on July 17, 2020, following a seven-month battle with pancreatic cancer. The 80-year-old dedicated his life to building what he called "The Beloved Community" in America — first as a civil rights leader and then as a lawmaker advocating, for reforms on issues from gun control to health care.

Over the years, there have been numerous attempts to create "glow-in-the-dark" plants. However, none of the approaches — which included infusing plants with nanoparticles of the luciferins and enzymes needed for the phenomenon to occur, or incorporating them with bacterial bioluminescence genes – proved feasible.

On July 18, 2020, about 150 Paris residents settled inside 38 electric boats floating on the Seine river to enjoy a free screening of Le Grand Bain — a 2018 comedy about a group of middle-aged men forming a synchronized swim team. The city's first "Cinema sur L'Eau," or "Cinema on Water," was organized by MK2 Cinemas to celebrate the June 22 reopening of the country's movie theaters, which had been shuttered since mid-March to stem the rapid spread of the novel coronavirus.

Even those not normally interested in astronomy will find it hard to resist NEOWISE, the brightest comet to grace our skies since the 1997 appearance of Comet Hale-Bopp. The spectacular cosmic snowball of frozen gas, rock, and dust has been visible to those willing to wake up before dawn since early July. However, it has now risen high in the evening skies and can be viewed with the unaided eye by even the most casual stargazer.

The solar system is about to get busy! In the next few weeks, a slew of spacecraft will embark on a one-way journey to Mars, to seek evidence of past life and to further investigate its unusual atmosphere. The back-to-back missions are timed to take advantage of the short window of opportunity — caused by celestial mechanics — that will allow them to reach the Red Planet in the most efficient and cost-effective manner.

The term "bird brain" is frequently used to describe a person's lack of intelligence and good decision-making ability. However, some scientists believe it should be considered a compliment, given that many birds can perform tasks that were once considered solely within the realm of humans. These include manufacturing and using tools, solving problems, and planning for future needs. Now, Griffin, an African Grey parrot, has proved that birds may even possess better visual memories than human adults and children.

One of the biggest challenges to battling the rapid spread of COVID-19 is identifying and isolating people who are infected before the symptoms, which usually take between 3 to 13 days, surface. Now, frontline workers may get some help from canines who can "sniff out" the disease even when the patient is asymptomatic, meaning he or she never shows any of the traits associated with COVID-19.

Former US President Ronald Reagan's love for jelly beans, which were a staple offering during his 8-year-term in office, is well-documented. However, the country's 40th head of state also had another guilty pleasure — ice cream, which he described as "[a] nutritious and wholesome food." To give the delicious treat the respect it deserved, on July 9, 1984, Mr. Reagan signed Proclamation 5219, which declared July as National Ice Cream Month!

A massive dust cloud that had been journeying 5,000 miles from the Sahara Desert across the Atlantic Ocean since June 15, 2020, finally hit the United States mainland on June 26, 2020. Nicknamed "Godzilla," the 3,500 mile-long plume broke into two chunks, thanks to the split in the mid-levels of the atmosphere.

Burying loved ones with basic necessities like grains, ceramic pots, and clothing, to ensure their comfort in the afterlife, was a fairly common tradition in ancient cultures. However, the families of some lucky individuals went a step further by including a board game for entertainment. Morten Ramstad, a researcher at the University of Bergen, Norway, and his team stumbled upon one of the rare artifacts — found only in a handful of graves before — while excavating the remains of an Early Iron Age (400-300 BC) burial mound in Western Norway.

Spain's three-month-long lockdown order imposed to curb the spread of the COVID-19 pandemic was finally lifted on June 22, 2020. To celebrate the joyous occasion, the Gran Teatre del Liceu in Barcelona, Spain — one of Europe's oldest and most famous opera houses— staged its first live performance since mid-March. While every seat was occupied, there was not a human to be found. Instead, the sold-out audience comprised 2,292 potted plants carefully selected from local nurseries.

With less than 55,000 grizzly bears left in the wild across North America, the sighting of even one is a cause for celebration. Hence you can only imagine how delighted Cara Clarkson and her family were when they spotted two young grizzlies — one with rarely seen all-white fur— foraging alongside the Trans-Canada Highway near Banff, Canada, on April 26, 2020.

June 19, 2020, marks the 155th anniversary of Juneteenth — a mashup of June and nineteenth — the oldest-known celebration commemorating the end of slavery in the United States. It was on this day in 1865 when the last American slaves — a group of people in Texas — finally learned that slavery had been abolished and that they were free.

The unwarranted death of George Floyd, an unarmed African American man, by a Minneapolis, MN, police officer on May 25, 2020, has reignited the debate about race-based police abuse. Protestors argue that the current law enforcement system encourages systemic racism and are calling for nationwide police reform. In addition to changing the laws, activists are also making a strong case for "defunding the police."

With the days getting increasingly longer and warmer, the Northern Hemisphere summer may seem to be well on its way. However, though the meteorological season, which evenly splits the 12 months of the year into four seasons, started on June 1, 2020, the astronomical summer will not begin until June 20, 2020. Called summer solstice, it is the day when the North Pole is most inclined towards the Sun, allowing residents of the Northern Hemisphere to enjoy the longest day (and shortest night) of the year. Conversely, Southern Hemisphere residents will celebrate the astronomical start of winter, or winter solstice, with the shortest day (and longest night) of 2020.