Evolutionary anachronism, also known as "ecological anachronism", is a term initially referring to attributes of certain plant species that possess traits seemed best explained as having been favorably selected in the past due to their coevolution with plant-eating megafauna that are now extinct. By far the most famous of these is the avocado, which is native to the Tropical Americas, but contains pits too large for even the largest currently living native frugivore, certain tapirs, but is readily consumed by Pleistocene megafaunal analogs (elephants, rhinos) if introduced to Africa and India.
The concept was formulated by Costa Rican-based American ecologist Daniel H. Janzen and carried broadly into scientific awareness when he and his coauthor, paleoecologist Paul S. Martin, published "Neotropical Anachronisms: The Fruits the Gomphotheres Ate" in the journal Science. Among the largest of extinct fruit-eating mammals in the American tropics were the gomphotheres, related to modern elephants, which inspired the title chosen by Janzen and Martin for their 1982 paper. As they explained,
Claims of gomphothere fruit consumption were validated in 2025 when teeth of the South American gomphothere Notiomastodon were found with the residue of Chilean cocopalm (Jubaea chilensis) fruit.
The Janzen and Martin paper was preceded by a 1977 publication by American ecologist Stanley Temple. Temple attributed the decline of the Mauritius endemic tree tambalacoque to human overharvesting to extinction of a large, flightless bird that had coevolved on the same tropical island: the dodo. It was Janzen who applied the concept to some 18 fruiting plant species or genera in Costa Rica, while Martin took the lead on proposing a distinct seed dispersal syndrome: the "megafaunal dispersal syndrome" by comparing the maladapted neotropical fruits with similar forms in the tropics of Africa and Asia that were documented as dispersed by elephants still inhabiting those continents.
Two decades after the "neotropical anachronisms" concept was published and named, science writer Connie Barlow aggregated its history and subsequent applications into a popular science book: The Ghosts of Evolution: Nonsensical Fruit, Missing Partners, and Other Ecological Anachronisms. In shaping the book's title, Barlow drew upon a 1992 essay by Paul S. Martin titled "The Last Entire Earth". Martin had written:
The honey locust mentioned in Martin's excerpt is a native tree of eastern North America. Because it is favored for planting along urban streets and parking lots, Barlow was very familiar with it while she was working on her book in New York City. Its long, curving pods became a prominent part of her book. Later, other writers also popularized its lost partnership with ice age "ghosts" (extinct fauna).
One animal-with-animal form of evolutionary anachronism also gained popular attention. As reported in the New York Times, "Pronghorn's Speed May Be Legacy of Past Predators", John A. Byers hypothesized that the antelope-like pronghorn of America's grasslands was still running from a Pleistocene ghost that had been much faster than America's native wolves. This ghost was the American cheetah.
Megafaunal dispersal syndrome
Seed dispersal syndromes are complexes of fruit traits that enable plants to disperse seeds by wind, water, or mobile animals. The kind of fruits that birds are attracted to eat are usually small, with only a thin protective skin, and the colors are red or dark shades of blue or purple. Fruits categorized as mammal syndrome are bigger than bird fruits. They may possess a tough rind or husk and emit a strong odor when ripe. Because mammals (other than primates) tend to have poor color vision, these fruits usually retain a dull coloration of brown, burnished yellow, orange, or will remain green when ripe. The megafaunal dispersal syndrome refers to those attributes of fruits that evolved in order to attract megafauna (animals that weigh or weighed more than 44 kilograms) as primary dispersal agents. Following the Late Pleistocene megafaunal extinctions, most species of large herbivores have become extinct outside of Africa (and to a lesser extent Asia), thereby reducing the effectiveness of seed dispersal—except for the fruits that attracted cultivation by humans.
Common megafaunal dispersal traits Large fruit, best suited to be consumed whole by large animals without seed loss. Fruit grows on or close to the trunk, or on stout branches. Indehiscent fruit that retains its seeds upon ripening. Seeds deter or elude being ground up by teeth through having a thick, tough or hard endocarp; or bitter, peppering or nauseating toxins. They are also difficult to separate from the pulp, which is tasty and soft, to deter seed spitting. The seeds benefit from—or even require—physical or chemical abrasion to germinate. If tropical, the fruit drops on or just before ripening, stopping monkeys from eating them. In colder climates, the fruit stays on the branch for a prolonged time, keeping it away from predation by ineffectual seed dispersers like rodents. "Looks, feels, smells, and tastes" like other fruits known to be dispersed by megafauna where megafauna still exists.
Ecological indicators of missing dispersal partners
The fruit either rots where it falls or is ineffectually disseminated by current dispersal agents. The plant is more common where livestock (proxy for megafauna) are present. The seeds germinate and grow well in upland habitats where planted, but the species almost exclusively inhabits floodplains (where water flow disperses the seeds) in the wild. The geographic range is inexplicably patchy or restricted.
Proposed examples in plants Afrotropical realm
Example Binomial name Native range Anachronism description Suggested extinct coevolutionary partners Balanites Balanites wilsoniana West and Central Africa Extremely limited or unrecorded seed dispersal in areas where elephants were extirpated; at least one Kenyan forest lacks seedlings and younger trees altogether. Forest elephant and bush elephant. Bottle palms Hyophorbe spp. Mascarene Islands Toxic, at least to humans, and resistant to trampling. Five species of giant tortoises of the genus Cylindraspis lived in the islands before they were hunted to extinction in the 18th and 19th centuries. Canarium paniculatum Mauritius Hard seeds and fleshy pulp. Though common in the high forest vegetation, it has a poor regeneration rate. Double coconut Lodoicea maldivica Praslin and Curieuse islands (Seychelles) The fruit weighs over 20 kg and contains the largest seeds in the world. No known animal eats the fruit, and the surviving trees appear to be the result of vegetative reproduction. Mature fruits do not float and are killed by sea water, unlike real coconuts. The species is not thought to have dispersed over water, but to have evolved locally in the Seychelles after they broke off from the Indian Plate 66 million years ago. No megafauna is known from the archipelago before the Seychelles giant tortoise arrived 23 million years ago; they eat much smaller fruit, and the distribution of tortoises and plants in the islands is inconsistent with co-dispersal.Bellot, Sidonie, et al. "On the origin of giant seeds: the macroevolution of the double coconut (Lodoicea maldivica) and its relatives (Borasseae, Arecaceae)." New Phytologist 228.3 (2020): 1134-1148. Île aux Aigrettes ebony Diospyros egrettarum Île aux Aigrettes off Mauritius Fruit eaten by introduced Aldabra giant tortoises, which disperse the seeds successfully. Cylindraspis. Latan palms Latania loddigesiiL. lontaroidesL. verschaffeltii Mascarene Islands One species per island, all with pyrena smaller than their relatives in continental Africa and Madagascar, which are dispersed by large mammals and birds; smaller fruits are consumed by tortoises. L. loddigesii is resistant to trampling. The colonization of each island by the palms coincides with the arrival of giant tortoises. Makak Mimusops petiolaris Mauritius In decline due to the absence of animals removing its pulp. The fruit is colonized by fungi hyphae and the seeds rot without germinating. The fruit is only sporadically consumed by the Mauritian flying fox, which does not ingest the seeds. Mascarene amaranth Aerva congesta Mauritius and RodriguesPynee, K. B., Lorence, D. H., & Khurun, P. (2018). Conservation status of Mascarene Amaranth Aerva congesta Balf. F. Ex Baker (Eudicots: Caryophyllales: Amaranthaceae): a Critically Endangered endemic herb of the Mascarenes, Indian Ocean. Journal of Threatened Taxa, 10(8), 12056-12063. Reduced to open barren areas on Round Island, its small prostrate form would protect it from grazing by tortoises. Cylindraspis. Mascarene grass Zoysia tenuifolia Mascarene Islands Ignored by introduced Aldabra giant tortoises in favor of other grasses. Cylindraspis. Mascarene tussock-grass Chrysopogon argutus Mascarene Islands Coarse, unpalatable leaves that are avoided by grazers like introduced rabbits when other grasses are available. Tussock-grass dominated Round Island before rabbits were removed, after which it immediately declined and was replaced by other native grasses.Cheke, A. & Hume, J.P. (2009) Lost land of the dodo: The ecological history of Mauritius, Réunion and Rodrigues. T & AD Poyser, London, 480 pages. Cylindraspis. Mauritius dragon tree Dracaena concinna Mauritius Resistant to trampling and capable of re-sprouting from damaged and flattened stems. Cylindraspis. Tambalacoque Sideroxylon grandiflorum Mauritius Peach-sized fruit that ripens from green to brown, much larger than its relatives present in the island and which are eaten by flying birds. The seed is in fact too large to be ingested by flying birds, and introduced pigs and monkeys destroy the seeds rather than disperse them. The tambalacoque evolved locally from smaller-seeded species of the genus Sideroxylon (formerly Calvaria), which is found in Africa and Madagascar. Temple reported in 1977 that only 13 trees were left, all of them over three hundred years old, and that seeds could not germinate at all without being ingested and abraded first. However, these claims have since been debunked. Temple proposed that the tambalacoque had a strict mutualist relation with the dodo, extinct since c.1662.Critics argued that the seeds were dispersed by a giant tortoise instead, and that the tambalacoque might even have descended from seeds contained in a tortoise drifting from Madagascar, as tortoises are buoyant and colonize islands easily. In the Galapagos, ingestion by giant tortoises reduces seed dormancy in the Galapagos wild tomato, Solanum galapagense. Two species of giant tortoise were present in Mauritius before being hunted to extinction in the 18th century, the saddle-backed and domed Mauritius giant tortoise. However, the seeds have a harder cover than those eaten by tortoises, which have no gizzard; this might imply to a mutualistic relation with a bird after all, and the dodo was the only bird large enough to ingest the seeds. In any case, it was later found that germination was not favored by ingestion and abrasion of the seeds, but by pulp removal. The fruit that remains whole is colonized by fungi and its seeds rot.The broad-billed parrot was also a large bird, although a flying one, and had an even more powerful beak than the dodo.The Mauritian giant skink is presumed to have been omnivorous.The coconut crab existed formerly in Mauritius, but has since disappeared from the island.
Madagascar