Short answer
Yes. Genetic studies show that fungi and animals share a more recent common ancestor with each other than either does with plants. Both belong to a supergroup called Opisthokonta. That's why fungi, like us, can't make their own food, store energy as glycogen, and build cell structures from some of the same materials, and why fungal infections are harder to treat than bacterial ones.
Key takeaways
- Animals and fungi are each other's closest major relatives, both in a group called Opisthokonta.
- Plants branched off earlier. A mushroom is more closely related to you than to a tree.
- Shared traits include eating other organisms instead of photosynthesizing and storing energy as glycogen.
- That kinship is why antifungal drugs are tricky: what harms a fungal cell often bothers ours.
Where fungi sit on the tree of life
For most of history, people lumped mushrooms in with plants. They don't move, they grow out of the ground, and they show up in the produce aisle. Genetics settled the question in the 1990s. When researchers compared protein sequences across many organisms, animals and fungi consistently came out as each other's closest relatives, with plants on a separate, earlier branch.12
Biologists now put animals and fungi together in a supergroup called Opisthokonta. In plain English: at some point more than a billion years ago, a single-celled ancestor gave rise to two lineages. One eventually led to you, and the other to every mushroom, mold, and yeast on Earth.3 Plants had already split off before that.
What you have in common with a mushroom
| Trait | Animals | Fungi | Plants |
|---|---|---|---|
| How they get energy | Eat other organisms | Absorb nutrients from other organisms | Photosynthesis |
| How they store energy | Glycogen | Glycogen | Starch |
| Chitin | Yes, in insect and crab shells | Yes, in cell walls | No |
| Swimming reproductive cells | One rear flagellum (sperm) | One rear flagellum (in some groups) | Different arrangement, or none |
None of this means mushrooms are secretly tiny animals. Fungi took a very different path, building bodies out of threadlike networks called mycelium and digesting food outside their bodies. But at the level of cells and genes, the family resemblance is real.
Why this matters for medicine
Here's the practical side. Antibiotics work well because bacteria are radically different from human cells, so drugs can hit them hard and leave us alone. Fungal cells are much more like ours, so finding drugs that kill fungi without harming people is harder. That's a big reason fungal infections can be stubborn and why some antifungal medicines have serious side effects.
It's also a fun way to think about psilocybin. Mushrooms make a molecule that fits into our serotonin receptors almost like a key cut for the lock. Nobody's sure why psilocybin evolved, though theories include deterring insects that eat mushrooms. Either way, the chemistry of our distant cousins turns out to speak our brain's language.
How far back does this go?
Fossils of what appear to be fungi have been found in rocks around a billion years old in Arctic Canada, consistent with an ancient origin.4 For the full story of fungi in the fossil record, from microscopic threads to the oldest known mushroom, read how old are mushrooms?
Common questions
Are mushrooms plants?
No. Fungi are their own kingdom. They don't photosynthesize, their cell walls are made of chitin instead of cellulose, and genetically they're closer to animals than to plants.
How long ago did animals and fungi split?
Estimates vary with the method, but molecular clock studies generally place the split more than a billion years ago, after the lineage leading to plants had already gone its own way.
What is Opisthokonta?
It's the group that includes animals, fungi, and several related single-celled organisms. The name refers to a shared trait: reproductive cells that swim with a single tail-like flagellum at the back, like a sperm cell or the spores of chytrid fungi.
Sources
- Baldauf SL, Palmer JD. Animals and fungi are each other's closest relatives: congruent evidence from multiple proteins. PNAS. 1993. doi.org/10.1073/pnas.90.24.11558
- Wainright PO, et al. Monophyletic origins of the metazoa: an evolutionary link with fungi. Science. 1993. doi.org/10.1126/science.8469985
- Parfrey LW, et al. Estimating the timing of early eukaryotic diversification with multigene molecular clocks. PNAS. 2011. doi.org/10.1073/pnas.1110633108
- Loron CC, et al. Early fungi from the Proterozoic era in Arctic Canada. Nature. 2019. doi.org/10.1038/s41586-019-1217-0
This article is for education only and is not medical or legal advice. Psilocybin is a Schedule I substance under U.S. federal law. Talk with a licensed clinician before making decisions about your health. In a crisis, call or text 988.