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The tree of life, with you in it

Which is your closer relative: a mushroom or a tomato?

Vote. Then type any living thing, from your plate, your garden or your own body, and see when its line parted from yours. 577 organisms, 35 branch points, from chimpanzees back to bacteria.

Your tree

Type what you ate today, what lives in your garden, what your biology teacher mentioned. Each living thing appears as a line that meets yours: the further left, the longer ago. The coloured band at the end of the line is the range the studies give. Tap a line to see its branch point.

Time on a logarithmic scale: each division is ten times further back than the one before. Otherwise the chimpanzee and the mushroom would not fit on the same screen.

The way back: all 35 branch points

If you walked back in time along your line, you would pass these branch points one after another. At each, another branch of life would join yours. A branch point marks where an ancestral population split into two lines; the ancestor has no name and is no living species, and the chimpanzee's line has been evolving for exactly as long as yours.

When did the common ancestor of humans and chimpanzees live?

About 6.9–9 million years ago, according to the molecular clock in a catalogue of genomes from 233 primate species (Kuderna et al. 2023). The population split is estimated at around 6, or at least 7–8, million years, depending on the mutation rate assumed (Scally et al. 2012; Langergraber et al. 2012). Individual genes part earlier.

6.9–9 million years ago chimpanzees and bonobos

The band is a molecular-clock estimate, slightly older than other recent analyses. The population split is estimated at ~6 million years (Scally et al. 2012) or at least 7–8 (Langergraber et al. 2012), depending on the mutation rate assumed. Individual genes diverged earlier (Moorjani et al. 2016: ~12 million years), because the variants already existed in the ancestral population.

Estimate on the tree: Kuderna et al. 2023, Science · Scally et al. 2012, Nature: ~6 (5.5–7, depending on the mutation rate) · Langergraber et al. 2012, PNAS: at least 7–8 · Fossil minimum: 6.5 million years (Benton et al. 2015, Palaeontologia Electronica)

In the index (2): bonobo, chimpanzee

8.8–11.2 million years ago gorillas

Estimate on the tree: Kuderna et al. 2023, Science · Scally et al. 2012, Nature: ~10 (8.5–12, depending on the mutation rate)

In the index (1): gorilla

18.6–22 million years ago orangutans

Estimate on the tree: Kuderna et al. 2023, Science · Fossil minimum: 11.6 million years (Benton et al. 2015, Palaeontologia Electronica)

In the index (1): orangutan

21–25 million years ago gibbons

Shared since then: None of the living apes (gibbons, orangutans, gorillas, chimpanzees, humans) has a tail.

Estimate on the tree: Kuderna et al. 2023, Science · Carbone et al. 2014, Nature: 15.9–17.6, assuming the macaque split at 29 million years · Fossil minimum: 11.6 million years (Benton et al. 2015, Palaeontologia Electronica)

In the index (2): gibbon, siamang

29–33 million years ago Old World monkeys: macaques, baboons

Shared since then: Close-set, downward-facing nostrils and the same dental formula: 32 adult teeth, with 2 incisors, 1 canine, 2 premolars and 3 molars in each half-jaw.

Estimate on the tree: Kuderna et al. 2023, Science · dos Reis et al. 2018, Systematic Biology: 30.4–35.1 · Fossil minimum: 24 million years (Benton et al. 2015, Palaeontologia Electronica)

In the index (7): baboon, colobus monkey, Japanese macaque, mandrill, proboscis monkey, rhesus macaque, vervet monkey

37–41 million years ago New World monkeys: capuchins, spider monkeys

Estimate on the tree: Kuderna et al. 2023, Science · dos Reis et al. 2018, Systematic Biology: 41.8–48.3 · Fossil minimum: 34 million years (Benton et al. 2015, Palaeontologia Electronica)

In the index (6): capuchin monkey, howler monkey, marmoset, spider monkey, squirrel monkey, tamarin

55–60 million years ago tarsiers

Shared since then: A dry nose, without a lemur's wet snout, and a broken gene for vitamin C: that is why we have to get it from food.

Estimate on the tree: Kuderna et al. 2023, Science

In the index (1): tarsier

58–63 million years ago lemurs and lorises

Shared since then: Grasping hands, and flat nails in place of claws on most fingers.

Did the primates split before or after the asteroid that ended the dinosaurs (all but the birds), 66 million years ago? The studies disagree: Kuderna et al. 2023 say after, dos Reis et al. 2018 before.

Estimate on the tree: Kuderna et al. 2023, Science · dos Reis et al. 2018, Systematic Biology: 70.0–79.2 · Fossil minimum: 56 million years (Benton et al. 2015, Palaeontologia Electronica)

In the index (4): aye-aye, galago, ring-tailed lemur, slow loris

63–68 million years ago colugos (flying lemurs)

Estimate on the tree: Kuderna et al. 2023, Science

In the index (1): colugo

66–71 million years ago treeshrews

Some analyses place treeshrews closer to rodents than to us.

Estimate on the tree: Kuderna et al. 2023, Science · Fossil minimum: 62 million years (Benton et al. 2015, Palaeontologia Electronica)

In the index (1): treeshrew

75–88 million years ago rodents and rabbits

Estimate on the tree: Foley et al. 2023, Science · Fossil minimum: 62 million years (Benton et al. 2015, Palaeontologia Electronica)

In the index (18): alpine marmot, brown rat, capybara, chinchilla, coypu, crested porcupine, edible dormouse, Eurasian beaver, European ground squirrel, European hare, gerbil, guinea pig, hamster, house mouse…
all 18alpine marmot, brown rat, capybara, chinchilla, coypu, crested porcupine, edible dormouse, Eurasian beaver, European ground squirrel, European hare, gerbil, guinea pig, hamster, house mouse, lemming, pika, rabbit, red squirrel

87–106 million years ago dogs, cats, cows, horses, bats, whales

Estimate on the tree: Foley et al. 2023, Science · Álvarez-Carretero et al. 2022, Nature: within the last 12 million years of the Cretaceous · Fossil minimum: 62 million years (Benton et al. 2015, Palaeontologia Electronica)

In the index (73): alpaca, American bison, Bactrian camel, blue whale, bottlenose dolphin, brown bear, cat, chamois, cheetah, common pipistrelle, common shrew, cow, dog, donkey…
all 73alpaca, American bison, Bactrian camel, blue whale, bottlenose dolphin, brown bear, cat, chamois, cheetah, common pipistrelle, common shrew, cow, dog, donkey, dromedary, Eurasian lynx, Eurasian otter, European badger, European bison, European mole, fallow deer, flying fox, gazelle, giant panda, giraffe, goat, golden jackal, harbour porpoise, harbour seal, hedgehog, hippopotamus, horse, humpback whale, jaguar, least weasel, leopard, lion, llama, Mediterranean monk seal, meerkat, mink, moose, mouflon, mule, narwhal, orca, pangolin, pig, pine marten, polar bear, polecat, puma, raccoon, red deer, red fox, reindeer, roe deer, sea lion, sheep, sperm whale, spotted hyena, stoat, tapir, tiger, vampire bat, walrus, water buffalo, white rhinoceros, wild boar, wildcat, wildebeest, wolf, zebra

90–115 million years ago elephants and armadillos

Shared since then: A long pregnancy fed through a placenta that lasts until birth. In most marsupials the placenta lasts only a few days; in kangaroos and wallabies somewhat longer.

Every recent molecular clock puts this split in the Cretaceous, before the asteroid. The oldest secure fossils of modern placentals come after it (61.6 million years).

Estimate on the tree: Foley et al. 2023, Science · Álvarez-Carretero et al. 2022, Nature: 77.6–83.3 · dos Reis et al. 2012, Proc. R. Soc. B: 88–90 · Irisarri et al. 2017, Nature Ecology & Evolution: 73–139 · Fossil minimum: 62 million years (Benton et al. 2015, Palaeontologia Electronica)

In the index (10): aardvark, African elephant, Asian elephant, dugong, giant anteater, manatee, nine-banded armadillo, rock hyrax, sloth, tenrec

168–178 million years ago kangaroos, koalas, opossums

Shared since then: Young are born alive, not hatched from eggs.

Estimate on the tree: dos Reis et al. 2012, Proc. R. Soc. B · Fossil minimum: 156 million years (Benton et al. 2015, Palaeontologia Electronica)

In the index (7): koala, red kangaroo, sugar glider, Tasmanian devil, Virginia opossum, wallaby, wombat

174–192 million years ago platypuses and echidnas

Shared since then: Hair and milk. The platypus makes milk too, though it lays eggs.

Estimate on the tree: dos Reis et al. 2012, Proc. R. Soc. B · Fossil minimum: 165 million years (Benton et al. 2015, Palaeontologia Electronica)

In the index (2): echidna, platypus

299–330 million years ago reptiles and birds: lizards, turtles, crocodiles, chickens

Shared since then: The amniotic egg: the embryo grows in its own sac of fluid. In us, that sac still exists, inside the womb.

Estimate on the tree: Irisarri et al. 2017, Nature Ecology & Evolution · Fossil minimum: 318 million years (Benton et al. 2015, Palaeontologia Electronica)

In the index (65): American alligator, barn swallow, boa constrictor, budgerigar, canary, chameleon, chicken, collared dove, common adder, common blackbird, common crane, common cuckoo, common nightingale, common pheasant…
all 65American alligator, barn swallow, boa constrictor, budgerigar, canary, chameleon, chicken, collared dove, common adder, common blackbird, common crane, common cuckoo, common nightingale, common pheasant, common quail, common raven, common starling, eagle-owl, emperor penguin, emu, Eurasian magpie, European pond turtle, golden eagle, goose, grass snake, great cormorant, great egret, great spotted woodpecker, great tit, great white pelican, greater flamingo, green iguana, green lizard, green sea turtle, grey heron, grey parrot, griffon vulture, Hermann's tortoise, herring gull, hooded crow, hoopoe, house sparrow, hummingbird, Indian peafowl, king cobra, kiwi (bird), Komodo dragon, leopard gecko, little owl, mallard, mute swan, Nile crocodile, nose-horned viper, ostrich, peregrine falcon, reticulated python, rock dove, sand lizard, skylark, slow worm, snake, sparrowhawk, tuatara, turkey, white stork

333–351 million years ago amphibians: frogs, salamanders

Shared since then: Four limbs with digits (snakes and caecilians later lost them).

Estimate on the tree: Irisarri et al. 2017, Nature Ecology & Evolution · Fossil minimum: 337 million years (Benton et al. 2015, Palaeontologia Electronica)

In the index (10): African clawed frog, axolotl, caecilian, common toad, European tree frog, fire salamander, fire-bellied toad, great crested newt, marsh frog, olm

408–419 million years ago lungfish

Estimate on the tree: Irisarri et al. 2017, Nature Ecology & Evolution · Fossil minimum: 408 million years (Benton et al. 2015, Palaeontologia Electronica)

In the index (1): Australian lungfish

413–444 million years ago the coelacanth

Shared since then: Fleshy fins with a single bone at the base. In your arm, that bone is the humerus.

Estimate on the tree: Irisarri et al. 2017, Nature Ecology & Evolution · Fossil minimum: 408 million years (Benton et al. 2015, Palaeontologia Electronica)

In the index (1): coelacanth

421–444 million years ago ray-finned fish: tuna, carp, salmon, seahorses

Shared since then: A skeleton of bone. Your lungs and the tuna's swim bladder come from the same organ.

Estimate on the tree: dos Reis et al. 2015, Current Biology · Fossil minimum: 421 million years (Benton et al. 2015, Palaeontologia Electronica)

In the index (34): Atlantic bluefin tuna, Atlantic cod, Atlantic herring, Atlantic mackerel, Atlantic salmon, beluga sturgeon, brown trout, chub, clownfish, common bream, common carp, Danube salmon, European anchovy, European eel…
all 34Atlantic bluefin tuna, Atlantic cod, Atlantic herring, Atlantic mackerel, Atlantic salmon, beluga sturgeon, brown trout, chub, clownfish, common bream, common carp, Danube salmon, European anchovy, European eel, European perch, goldfish, guppy, northern pike, Pontic shad, Prussian carp, pufferfish, red-bellied piranha, round goby, Russian sturgeon, sardine, seahorse, starry sturgeon, sterlet, swordfish, tench, turbot, wels catfish, zander, zebrafish

433–469 million years ago sharks and rays

Shared since then: Jaws, and immunoglobulin antibodies. Lampreys and hagfish defend themselves with different receptors, built another way.

Estimate on the tree: dos Reis et al. 2015, Current Biology · Fossil minimum: 421 million years (Benton et al. 2015, Palaeontologia Electronica)

In the index (6): chimaera, common stingray, giant manta ray, great white shark, spiny dogfish, whale shark

460–528 million years ago lampreys and hagfish

Shared since then: A skull around the brain.

Estimate on the tree: dos Reis et al. 2015, Current Biology · Fossil minimum: 458 million years (Benton et al. 2015, Palaeontologia Electronica)

In the index (2): hagfish, sea lamprey

517–584 million years ago sea squirts

A sea squirt's larva swims like a tadpole; the adult settles down and looks like a bag.

Estimate on the tree: dos Reis et al. 2015, Current Biology · Fossil minimum: 514 million years (Benton et al. 2015, Palaeontologia Electronica)

In the index (2): salp, sea squirt

555–611 million years ago lancelets

Shared since then: The notochord, a stiff rod along the back. You had one too, as an embryo.

Estimate on the tree: dos Reis et al. 2015, Current Biology · Fossil minimum: 514 million years (Benton et al. 2015, Palaeontologia Electronica)

In the index (1): lancelet

594–628 million years ago sea stars and sea urchins

Estimate on the tree: dos Reis et al. 2015, Current Biology · Fossil minimum: 516 million years (Benton et al. 2015, Palaeontologia Electronica)

In the index (6): acorn worm, brittle star, sea cucumber, sea lily, sea urchin, starfish

615–638 million years ago insects, spiders, octopuses, snails, earthworms

Shared since then: A body with a front and a back, a left and a right.

Estimate on the tree: dos Reis et al. 2015, Current Biology · Fossil minimum: 550 million years (Benton et al. 2015, Palaeontologia Electronica)

In the index (69): Antarctic krill, aphid, bed bug, black widow, blue mussel, bumblebee, C. elegans, cabbage white, castor bean tick, cat flea, centipede, chambered nautilus, cicada, clothes moth…
all 69Antarctic krill, aphid, bed bug, black widow, blue mussel, bumblebee, C. elegans, cabbage white, castor bean tick, cat flea, centipede, chambered nautilus, cicada, clothes moth, cockchafer, Colorado potato beetle, common octopus, common wasp, cuttlefish, dragonfly, earthworm, European hornet, European lobster, field cricket, firefly, fruit fly, garden spider, German cockroach, grain weevil, great green bush-cricket, great scallop, head louse, honey bee, horseshoe crab, house dust mite, housefly, liver fluke, mayfly, medicinal leech, migratory locust, millipede, monarch butterfly, mosquito, noble crayfish, oyster, pinworm, planarian, pork tapeworm, praying mantis, red wood ant, Roman snail, rotifer, roundworm, scorpion, seven-spot ladybird, shore crab, shrimp, silkworm, slug, squid, stag beetle, swan mussel, tarantula, tardigrade, termite, tiger mosquito, trichina worm, water flea, woodlouse

631–653 million years ago jellyfish, corals, sea anemones

Estimate on the tree: dos Reis et al. 2015, Current Biology · Fossil minimum: 550 million years (Benton et al. 2015, Palaeontologia Electronica)

In the index (7): barrel jellyfish, hydra, moon jellyfish, Portuguese man o' war, red coral, sea anemone, staghorn coral

681–833 million years ago sponges and comb jellies

Shared since then: A body of many cells stuck together, grown from an egg fertilised by a sperm.

Which branched off first, sponges or comb jellies? Schultz et al. 2023 say comb jellies. If they are right, the sponge's line parted from yours somewhat later, at a date no study gives separately.

Estimate on the tree: dos Reis et al. 2015, Current Biology · Fossil minimum: 550 million years (Benton et al. 2015, Palaeontologia Electronica)

In the index (6): bath sponge, Beroe, comb jelly, freshwater sponge, sea sponge, warty comb jelly

No separate date: after 1.24–1.48 billion years ago, before 681–833 million years ago choanoflagellates

The ancestor: A cell with one flagellum and a collar of microvilli, perhaps sometimes living in colonies.

In the index (2): choanoflagellate, Monosiga

No separate date: after 1.24–1.48 billion years ago, before 681–833 million years ago ichthyosporeans and Capsaspora

In the index (2): Capsaspora, ichthyosporean

1.24–1.48 billion years ago fungi: button mushrooms, yeast, moulds

The ancestor: A single cell that swam pushed by one flagellum at the rear.

Shared since then: Cells that swim have a single flagellum, at the rear: your sperm cells, and the spores of chytrid fungi.

Estimate on the tree: Parfrey et al. 2011, PNAS · Betts et al. 2018, Nature Ecology & Evolution: 1.13–1.71 billion

In the index (27): Aspergillus, baker's yeast, blue cheese mould, bread mould, button mushroom, Candida, chanterelle, chytrid fungus, corn smut, death cap, ergot, fly agaric, grey mould, honey fungus…
all 27Aspergillus, baker's yeast, blue cheese mould, bread mould, button mushroom, Candida, chanterelle, chytrid fungus, corn smut, death cap, ergot, fly agaric, grey mould, honey fungus, lichen, morel, Nosema, oyster mushroom, Penicillium, porcini, powdery mildew, reindeer lichen, shiitake, tinder fungus, truffle, wheat rust, zombie-ant fungus

No separate date: after 1.68–1.87 billion years ago, before 1.24–1.48 billion years ago slime moulds and amoebae: Physarum, Dictyostelium

Parfrey et al. 2011, PNAS: older than the amoebozoan crown, 1.38–1.62 billion

In the index (5): Acanthamoeba, amoeba, Entamoeba, slime mould, slime mould Dictyostelium

1.68–1.87 billion years ago plants, algae and all other eukaryotes: bananas, tomatoes, oaks, the malaria parasite

The ancestor: A single cell that already had a nucleus, mitochondria and flagella. Reconstructed from the genes its descendants share, not from fossils.

Where the root of the eukaryote tree lies is still argued (Derelle et al. 2015; Al Jewari & Baldauf 2023). For plants, the meeting with your line is either the ancestor of all living eukaryotes or a slightly later branching. The order does not change: the plant parted from you before the fungus did.

Estimate on the tree: Parfrey et al. 2011, PNAS · Betts et al. 2018, Nature Ecology & Evolution: 1.21–1.84 billion · Strassert et al. 2021, Nature Communications: 1.96–2.39 billion

In the index (163): agar alga, almond, apple, apricot, ash, aubergine, avocado, bamboo, banana, baobab, barley, basil, beech, beetroot…
all 163agar alga, almond, apple, apricot, ash, aubergine, avocado, bamboo, banana, baobab, barley, basil, beech, beetroot, bilberry, black locust, blackberry, bladderwrack, bracken, brain-eating amoeba, broccoli, cabbage, cacao, cactus, carrot, cauliflower, celery, chamomile, chickpea, Chlamydomonas, Chlorella, coccolithophore, coffee, common bean, common poppy, cotton, courgette, cucumber, dandelion, diatom, dill, dinoflagellate, dog rose, duckweed, edelweiss, elder, Euglena, European larch, fig, flax, foraminiferan, garlic, geranium, giant sequoia, Giardia, ginkgo, gooseberry, grapefruit, grapevine, grapevine downy mildew, grass, hazel, hemp, hornbeam, horse chestnut, horsetail, juniper, kelp, kiwifruit, kombu, lavender, leek, Leishmania, lemon, lentil, lettuce, lilac, linden, lovage, Madonna lily, maize, malaria parasite, mandarin, mango, maple, melon, mint, mistletoe, moss, mountain pine, nori, Norway spruce, oak, oat, olive, onion, orange, orchid, paramecium, parsley, pea, peach, peanut, pear, peat moss, peony, pepper, pineapple, plum, poplar, potato, potato blight, pumpkin, quince, radiolarian, radish, rapeseed, raspberry, redcurrant, reed, rice, rose, rosemary, rye, sage, sargassum, Scots pine, sea lettuce, sea sparkle, silver birch, silver fir, snowdrop, sour cherry, soybean, spinach, Stentor, stinging nettle, stonewort, strawberry, sugarcane, sundew, sunflower, sweet cherry, sweet chestnut, tea plant, thale cress, thyme, tobacco, tomato, Toxoplasma, Trichomonas, Trypanosoma, tulip, Venus flytrap, Volvox, Vorticella, walnut, water lily, watermelon, wheat, white clover, willow, yew

No separate date: after 4.09–4.33 billion years ago, before 1.68–1.87 billion years ago archaea: methanogens, Asgard archaea

Your cells descend, by most recent analyses, from an archaeon of the Asgard group (Eme et al. 2023) that took a bacterium inside. When is not dated.

In the index (7): Asgard archaea, Halobacterium, methanogen, Nitrosopumilus, Pyrococcus, rumen methanogen, Sulfolobus

4.09–4.33 billion years ago bacteria: E. coli, the lactobacilli in yogurt, cyanobacteria

The ancestor: “A prokaryote-grade anaerobic acetogen that possessed an early immune system”, in the reconstruction of Moody et al. 2024. Inferred, not observed.

Shared since then: The same genetic code: the same three DNA letters mean the same amino acid in the genes of your cell nuclei and in E. coli.

Estimate on the tree: Moody et al. 2024, Nature Ecology & Evolution · Betts et al. 2018, Nature Ecology & Evolution: 4.48–4.52 billion, with 4.52 set as a limit by the study

In the index (25): Bifidobacterium, botulism bacterium, cholera bacterium, cyanobacteria, Deinococcus, E. coli, hay bacillus, Helicobacter pylori, Lactobacillus acidophilus, Lactobacillus bulgaricus, Listeria, Lyme disease bacterium, plague bacterium, pneumococcus…
all 25Bifidobacterium, botulism bacterium, cholera bacterium, cyanobacteria, Deinococcus, E. coli, hay bacillus, Helicobacter pylori, Lactobacillus acidophilus, Lactobacillus bulgaricus, Listeria, Lyme disease bacterium, plague bacterium, pneumococcus, Prochlorococcus, Rhizobium, Salmonella, spirulina, Staphylococcus aureus, Streptococcus, Streptococcus thermophilus, Streptomyces, tetanus bacterium, tuberculosis bacterium, Wolbachia

Do we share 60% of our DNA with bananas?

No. The figure comes from an unpublished comparison made at the US National Human Genome Research Institute (NHGRI) for a Smithsonian museum film. It compared proteins, not DNA: more than 4 million comparisons gave about 7,000 good pairs. The proteins in those pairs are, on average, about 40% identical, the geneticist Lawrence Brody explained.

“60%” came to mean the share of our genes that have a recognisable counterpart in the banana. A stricter count using three different methods (Natasha Glover, Dessimoz lab, 2020) finds a counterpart for 17–24% of human genes: a quarter at most. And the stretches of DNA that code for proteins are only about 1–2% of the genome; compare all the DNA and the share would be far smaller.

The genes we do share do what every cell does: break down sugar, copy DNA, build proteins. We have them from an ancestor that lived 1.68–1.87 billion years ago, according to Parfrey et al. 2011; other studies range from 1.2 to 2.4 billion years.

Are we related to bacteria?

Yes, twice. First through LUCA, the last common ancestor of all cellular life today, which lived 4.09–4.33 billion years ago by the estimate of Moody et al. 2024. From it we have the same genetic code as E. coli.

The second time is closer: your cells, except red blood cells, typically hold hundreds or thousands of mitochondria, and mitochondria were once free-living bacteria, relatives of the group called alphaproteobacteria. One of them ended up inside your ancestor 1.21–2.05 billion years ago (Betts et al. 2018) and never left. Mitochondria still carry their own small DNA, in practice inherited only from the mother. E. coli is not in that group, so it appears on the tree only once.

Plants did the same thing a second time: the chloroplasts in a banana leaf were once cyanobacteria. Their line split from the other cyanobacteria about 2.1 billion years ago (Sánchez-Baracaldo et al. 2017), and the adoption came on the plant branch, after it had parted from ours. Some clocks put the adoption earlier than Parfrey's date for our split from plants: one more place where the dates disagree and the order holds.

Are mushrooms closer to animals or to plants?

To animals. The plant line parted from ours before the fungus line did, so fungi and animals share a more recent common ancestor. That does not mean mushrooms resemble us; it means we parted later. The common ancestor, as reconstructed, was a single cell that swam pushed by one flagellum at the rear. Sperm cells swim the same way.

How is the order known?

From genes. Hundreds or thousands of genes are compared across many species, and statistical models of how genes change are used to find the tree that best fits the data. The shape of the tree, who parted before whom, is far more secure than the dates; only a few branchings are still argued: the treeshrew, sponges versus comb jellies, the root of the eukaryotes.

How is the date known?

From two sources that do not always agree. Fossils give a minimum age: if a 550-million-year-old fossil already belongs to a branch, the branching is at least that old. Molecular clocks give an estimate: how many differences have built up between genes, divided by the rate at which they build up, a rate calibrated on fossils. For the first animals the clocks say 681–833 million years, while the oldest fossils accepted as animals are about 558 million years old (Dickinsonia, Bobrovskiy et al. 2018). For placental mammals, the clocks say the splits began before the asteroid that ended the dinosaurs (all but the birds), while secure fossils appear only after it. That is why the tree draws bands, not points.

For teachers: one lesson with the tree

  1. The vote (10 minutes). Project the page and let the class vote by show of hands on each of the four questions before you tap. By the second or third, the class starts to suspect a trick; ask why.
  2. The class tree (15 minutes). Each student names a living thing: what they ate, a pet, something seen in the woods. Type them all. Then ask: which parted from us longest ago? Which is closer to us, the oak or the yeast?
  3. Order versus date (10 minutes). Show that in some studies the fungus and plant bands overlap, but the order never changes. Ask which is more certain, and why.
  4. What we share (10 minutes). Pick three branch points in “The way back” and read what all the descendants share: the notochord, jaws, the amniotic egg. Who can find them on their own body?

The tree's link can be copied: students open it at home with exactly the living things chosen in class.

Sources and method

Each living thing in the index sits at the branch point where its line parts from the human line, following current classification. For each branch point, the band on the tree comes from a single study per stretch of the road (primates: Kuderna et al. 2023; placentals: Foley et al. 2023; mammals: dos Reis et al. 2012; tetrapods and lobe-finned fish: Irisarri et al. 2017; other animals: dos Reis et al. 2015; eukaryotes: Parfrey et al. 2011; LUCA: Moody et al. 2024), so that bands do not overlap merely because methods differ. Other estimates are given in the text. Intervals are 95% credible or confidence intervals, with three exceptions: for eukaryotes (Parfrey et al. 2011) the band spans the mean estimates of the study's analyses; for placentals (Foley et al. 2023) it is the average of the bounds across 316 analyses; Scally et al. 2012's ranges cover different mutation rates.

Common names can cover several species; each row carries the scientific name of the species chosen. Divergence dates keep being revised: for any particular pair, TimeTree (timetree.org) gathers hundreds of studies.

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