Mushrooms have more in common with animals

Fungi and animals share an evolutionary branch

The resemblance between a mushroom and a plant is mostly a matter of appearance. Mushrooms are fungi, a separate kingdom of life. In evolutionary terms, fungi and animals share a more recent common ancestor with each other than either does with plants. That ancestor lived long ago; it was not a mushroom or an animal as we know them today.

A family tree records shared ancestry, not how much two organisms look alike or how closely they interact. Wheat and mushrooms can grow side by side, and people can eat both, but those everyday connections do not make them close relatives. The relevant question is which ancestral populations their lineages split from most recently.

The cellular clue: fungi do not make their own food

Plants use photosynthesis to turn light, water, and carbon dioxide into sugars. Fungi cannot do that. Instead, they release enzymes—molecules that break down food—into their surroundings, then absorb the resulting nutrients. A mushroom is the visible reproductive structure of a fungus; much of the organism may consist of fine threads called hyphae, spreading through soil, wood, or another food source.

Animals also obtain energy from organic material rather than making sugars with sunlight. But fungi and animals do this differently: animals typically take food into their bodies and digest it internally, while fungi digest material outside their bodies and absorb it. Their shared reliance on organic food reflects biology they inherited from a common lineage, not a shared modern lifestyle.

A surprising family resemblance

Fungi and animals also share features in their cells and basic molecular machinery that distinguish them from plants. No single trait, by itself, tells the whole evolutionary story; scientists infer relationships by comparing many characteristics, including DNA. Together, those comparisons place fungi closer to animals than to plants.

So the pizza comparison has a precise twist: the mushroom topping and the person delivering the pizza belong to closer evolutionary branches than the mushroom and the wheat in the crust. The ingredients can share a meal without sharing a recent family tree.