Tree of Life

Every living thing descends from a single last universal common ancestor — a cell that already ran on DNA, RNA, proteins, and the genetic code. From it the three great domains branched.

from Life (LUCA)

Single-celled organisms without a nucleus, the most abundant life on Earth. They drive nearly every chemical cycle and live everywhere from soil to the human gut.

from Bacteria

The first organisms to photosynthesise with oxygen as a by-product. Over two billion years they filled the air with oxygen and, engulfed by other cells, became the chloroplasts of all plants.

from Life (LUCA)

Prokaryotes that look like bacteria but are molecularly distinct — and closer kin to us. Many thrive in extreme heat, salt, or acid, and the eukaryotic lineage arose from within their ranks.

from Life (LUCA)

Organisms whose cells keep their DNA in a nucleus and run on mitochondria — captured bacteria turned power plants. From this single innovation came protists, plants, fungi, and animals.

from Eukaryota

A catch-all for eukaryotes that are neither plant, fungus, nor animal — amoebae, algae, ciliates, and slime moulds. Not a true branch but the diverse stock from which the visible kingdoms grew.

from Eukaryota

Multicellular photosynthesisers descended from green algae. When they colonised land, they built the soils, forests, and oxygen budget on which all terrestrial life depends.

from Plants

Small, rootless plants — mosses, liverworts, hornworts — that still need water to reproduce. As the earliest colonists of land, they hint at how the first plants lived.

from Plants

The first plants with true vascular tissue to carry water, letting them grow tall. They dominated the Carboniferous forests whose remains became today's coal.

from Plants

Seed plants — conifers, cycads, ginkgo — that freed reproduction from standing water. Their seeds sit exposed on cones rather than enclosed in fruit.

from Plants

Flowering plants that enclose seeds in fruit and recruit animals to pollinate and disperse them. Their partnership with insects made them the dominant plants — and the source of most human food.

from Eukaryota

Neither plant nor animal, fungi feed by absorbing nutrients through thread-like hyphae. As the great decomposers — and partners of plant roots — they recycle the dead and knit forests together.

from Eukaryota

Multicellular eukaryotes that eat other organisms and, mostly, move. From a common ancestor came every creature from sponges to humans, exploding in variety in the Cambrian.

from Animals

Animals without a backbone — sponges, jellyfish, worms, molluscs, insects. They make up the overwhelming majority of species and every major body plan except the vertebrate one.

from Invertebrates

Jointed-legged animals in a hard external skeleton — the most numerous and diverse animals on Earth. Insects alone outnumber all other animal species combined.

from Animals

Animals that, at least as embryos, have a stiffening rod (notochord) and a dorsal nerve cord along the back. This body plan set the stage for the backbone and the vertebrates.

from Chordates

Chordates that replaced the notochord with a bony or cartilaginous spine protecting the nerve cord. The braincase and jointed skeleton let them grow large and complex — fish, amphibians, reptiles, birds, mammals.

from Vertebrates

Gilled, fin-bearing vertebrates and the stock from which all land animals came. One group of lobe-finned fish crawled ashore and gave rise to every four-limbed creature.

from Vertebrates

The first vertebrates to walk on land, yet still tied to water to lay their jelly-like eggs. Frogs, toads, and salamanders live a double life between pond and shore.

from Vertebrates

Scaly vertebrates whose shelled, self-contained amniotic egg freed reproduction from water entirely. They ruled the Mesozoic as dinosaurs and still include lizards, snakes, turtles, and crocodiles.

from Reptiles

Feathered, warm-blooded descendants of theropod dinosaurs — the only branch of that great lineage to survive the mass extinction. Flight, song, and hollow bones set them apart.

from Vertebrates

Hair-covered vertebrates that nurse their young on milk and keep a constant body temperature. Small and nocturnal beside the dinosaurs, they radiated after the extinction into whales, bats, and humans.