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More than half of the world’s population live in urban areas where nature can feel like a distant concern.

Thriving ecosystems do, however, exist within our cities — even beneath our feet — and embracing urban nature can be a powerful force for change.

For example, West London has its first beaver dam in 400 years after the reintroduction of a family of five in October to a wetland on the city’s outskirts. The industrious beavers could help to prevent flooding after heavy rainfall.

Our Shared Home was the theme this week for CNN’s third annual Call to Earth Day, during which the network highlighted the crucial connection between cities and wilderness.

Once upon a planet

Chacma baboons overlook Cape Town, South Africa, from a hillside.

Baboon Matters

Interactions between urban dwellers and wildlife don’t always run smoothly.

Cape Town’s baboons can often be found rummaging through garbage cans and around backyards, putting them at greater risk of conflict with humans.

For the primates, the raiding behavior makes some sense — the suburbs encroach on their feeding grounds. Easy access to food from Cape Town’s trash means baboons spend less time and energy foraging, and more on socializing with potential mates and the rest of their group.

However, there are consequences for the baboons. Their health and welfare can suffer as the primates come into contact with dogs, cars and electric power lines. Some baboons have even been shot.

The city has begun taking proactive measures to keep them away from Cape Town’s outskirts and in their natural hillside habitat.

Fantastic creatures

Much nature photography focuses on the wild wonders of Earth and its majestic biodiversity.

Two photographers whose works CNN profiled as part of the Call to Earth initiative took a different approach. They captured intimate views of wildlife in an urban habitat.

Photographer Corey Arnold discovered a bear denning in a California home’s crawl space, while in the lush hillsides of Hong Kong’s New Territories, Lawrence Hylton recorded a collared scops owl, a white-lipped pit viper and an Atlas moth during his nocturnal safaris through Shing Mun Country Park.

The stunning, and sometimes amusing, images show how smart some animals are at adapting to a human-dominated landscape.

Look up

An image of the rare Steve phenomenon captured by Canadian photographer Neil Zeller.

Courtesy Neil Zeller

The sun is entering a period of heightened activity, making it easier to witness dazzling natural displays like the northern lights or their counterpart in the Southern Hemisphere.

There have also been sightings of an even rarer night-sky phenomenon that occasionally accompanies auroras. Known as Steve, it appears closer to the equator than polar auroras and is characterized by a purple-pink arch and green vertical stripes.

The mysterious light show was formally identified less than a decade ago, and explanations of what causes it are still taking shape.

The phenomenon’s name also has an unusual origin story involving a 2006 DreamWorks movie.

Across the universe

Astronomers have discovered six planets around a nearby sunlike star with orbits that haven’t changed for more than 1 billion years.

Larger than Earth but smaller than Neptune, the exoplanets are in a little-understood class called sub-Neptunes commonly found in the Milky Way.

As the planets revolve around their host star, which is about 100 light-years away from Earth, they display a pattern known as orbital resonance. This is when the planets complete their orbits and exert gravitational forces on one another, creating a harmonic rhythm, with all six planets aligning every few orbits.

Scientists believe the discovery could help unravel mysteries of planet formation.

Trailblazers

A colored image shows the multicellular structure of an anthrobot. Its surface cilia enables it to move and explore its environment.

Gizem Gumuskaya Tufts University

Scientists have created tiny living robots from human cells that can move around in a lab dish and may one day be able to help heal wounds or damaged tissue, according to a new study.

A team at Tufts University and Harvard University’s Wyss Institute have dubbed their creations anthrobots.

The research builds on the first living robots, or xenobots, which were made from stem cells sourced from the embryos of African clawed frogs.

However, the human cell-based bots differ in several ways from their froggy forerunners, and they displayed a behavior that surprised scientists.

Explorations

Check out these remarkable stories:

— Celebrate the trailblazing achievements of NASA astronaut Dr. Mary Cleave, who died November 27. She was the first woman to fly on the space shuttle after the Challenger disaster.

— Oceanographers have mapped an underwater mountain off the coast of Guatemala that is nearly twice the height of the world’s tallest building.

— A 19th century Tasmanian colonist came to be known as an accomplished scientist, but letters have now revealed the gruesome cost.

— Fossilized footprints suggest mystery animals once walked around on birdlike feet, long before the earliest known avian species appeared, paleontologists say.

Like what you’ve read? Oh, but there’s more. Sign up here to receive in your inbox the next edition of Wonder Theory, brought to you by CNN Space and Science writers Ashley Strickland and Katie Hunt. They find wonder in planets beyond our solar system and discoveries from the ancient world.

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