Go to the Ant Farm, Thou Darwinist
It’s the 50th anniversary of the Ant Farm, and inventor Milton Levine is still tickled about the impact his toy has had on millions of kids, reported AP on MSNBC. The charm of Uncle Milton’s Ant Farm was in “creating a whole world that you can see,” a world of creative and industrious ants. Moms didn’t mind too much as long as the ants stayed confined.
Serendipitously or not, Philip Ward (UC Davis) published a primer on ants in Current Biology.1 “Ants are one of evolution’s great success stories,” he began, but while his article had a lot to say about ant evolution, the actual evidence he presented seemed equivocal or imaginary. Some excerpts:
- Because they are fully social, ants do not tell us a great deal about the transition from solitary to eusocial behavior…. Regardless of the details of this sequence of events, which of course was played out long ago [sic], contemporary ants offer abundant opportunity for comparative studies of colony life after the eusocial threshold has been crossed.
- The point to emphasize is that since their divergence from a common ancestor [sic] in the Cretaceous, some ant lineages – such as the iconic army ants and leaf-cutting ants – have evolved [sic] quite complex societies while others, such as the ‘primitive’ [sic] bulldog ants of Australia, have remained at a much less advanced level. The factors responsible for such heterogeneity in the rate of social evolution [sic] have been little explored, and will require a careful analysis of ecological and phylogenetic influences.
- Ants are treated as a single family, Formicidae, in the order Hymenoptera, a large and diverse group of holometabolous insects…. Apocritan Hymenoptera exhibit a unique reorganization of the body parts in which the middle tagma [a functionally integrated set of body segments] is composed of the thorax plus abdominal segment 1, while the posterior tagma comprises the remaining abdominal segments. It is unclear how this evolutionary novelty arose, but one apparent consequence is that additional constrictions, involving abdominal segments 2�4, evolved [sic] in some apocritans, giving them exceptional dexterity of abdominal movement.
- Ants differ from social bees and wasps in one important respect: the workers of ants are entirely wingless. This places constraints on their foraging behavior and has probably spurred the evolution of complex chemical communication systems [sic], such as trail and recruitment pheromones, designed for terrestrial (as opposed to aerial) movement.
- There is little doubt that ants are a monophyletic group. They share a distinctive suite of morphological features, including geniculate (elbowed) antennae, a prognathous (forward-projecting) head, a characteristic configuration of the foretibial antenna cleaner, modification of the second abdominal segment to form a node-like petiole, and several unique exocrine glands. Yet the closest living relatives of ants have not been unequivocally identified. Several other families of aculeate Hymenoptera, in a subgroup known as the Vespoidea, have been touted as possible sister groups of ants including Tiphiidae, Bradynobaenidae and the combination of Vespidae plus Scoliidae. It is a measure of the incompleteness of our phylogenetic knowledge that none of these alternatives has particularly strong support. In many respects the summary cladogram published by Fredrik Ronquist in 1999, which depicted most vespoid families emerging out of an unresolved bush, still applies today.
- The fossil record helps to explain this impasse. Most families of aculeate wasps appear rather suddenly in the early Cretaceous, suggesting that there was a rapid burst of diversification once the sting had evolved. Ants make their appearance a little later, about 100 million years ago [sic].
- A more extensive series of fossil ants has now been documented from the Cretaceous. The fossils range in age from about 78 to 100 million years, and they include some undoubted crown-group taxa. Among the more spectacular finds are additional well preserved specimens from New Jersey amber, including representatives of the modern subfamily Formicinae, as well as fossils from Canada, Eurasia, and southern Africa. This taxonomic diversity and geographic spread indicates that crown-group ants arose some time before this period, perhaps as long ago as 120 million years. [sic]
- One might expect that the phylogenetic relationships among living representatives of Formicidae have been reasonably well clarified. In fact many uncertainties persist here too, and this is an area of active investigation and debate. Morphological studies have been helpful in circumscribing the major lineages (subfamilies) of ants, but the relationships among them have largely eluded confident resolution.
- Molecular data, in the form of DNA sequences from multiple nuclear genes, are just now being applied to the problem. Such data confirm the monophyly of nearly all of the subfamilies, but they also reveal a number of novel and unexpected groupings.
- Another insight to emerge from molecular phylogenetic analyses of ants is that there has been profound morphological convergence in some aspects of worker morphology, to the extent that it misled earlier phylogenetic inferences. For example, a constriction between abdominal segments 3 and 4, and the formation of a second node-like structure (a postpetiole), has evolved repeatedly [sic] in ants.
- The new phylogenetic estimates, combined with fossil-calibrated [sic] molecular dating analyses, suggest that the history of ants involves a series of sequential diversifications: evolution of sphecomyrmine and poneroid-like lineages in the early Cretaceous, about 100�120 million years ago, followed by a more exuberant diversification of formicoids beginning about 100 million years ago and continuing into the Paleogene…. In short, while the stem lineages of modern ant subfamilies were present before the K�T boundary, the ecological dominance and range of diversity that we associate with modern ants did not arise until later in the Tertiary, about 60�70 million years after ants first evolved. [sic]
- Several commentators have argued compellingly that the social behavior of ants is responsible at least in part for their evolutionary success [sic] and ecological dominance. Eusociality confers marked advantages in terms of resource acquisition, defense against enemies, and buffering of environmental variation. The division of labor and flexibility of task allocation that are the hallmarks of advanced social insects enable them to meet contingencies and exploit opportunities much more efficiently than solitary insects.
But this cannot be the entire story. Even among social insects ants are especially notable for their abundance and diversity, so additional factors must be invoked to explain their particular prominence.
- One can imagine that if formicoids had not evolved [sic], ants would be perceived as a modest group of tropical wingless wasps (with no vernacular term reserved for them), as opposed to the near-ubiquitous ecological dominants that we know today. But, then again, maybe another poneroid would have stepped in to fill the void. (Emphasis added in all quotes.)
One of the “spectacular finds” Ward mentioned was a formicoid ant found in Cretaceous New Jersey amber.2 More were announced in 2005 in New Jersey and Canada.3 For all practical purposes, these ants in amber look entirely modern, so any division into “primitive” or “advanced” seems a judgment call. Prior to this find, formicoids (those that produce formic acid as a defense) were thought to be much more recent. This also means that in the evolutionary scheme essentially modern ants evolved in the age of dinosaurs, survived the mass extinction at the end of the Cretaceous, evolved little for 60 million years, then exploded into a diverse and widespread group 40 million years ago. For the essentially parallel appearance of all the ant groups, see this phylogenetic diagram from the Tree of Life website. See also our related story on army ants from 05/06/2003.
In addition to his evolutionary speculations, Ward provided some “gee-whiz” facts about ants sure to fascinate ant farmers. There are about 20,000 species inhabiting a range of habitats from deserts to tropical rain forests:
They impose a strong ecological footprint in many communities in their varied roles as scavengers, predators, granivores, and herbivores. In some tropical forests the biomass of ants exceeds that of terrestrial vertebrates by a factor of four, and their soil-turning activities dwarf those of earthworms. There is a word for ‘ant’ in most languages, reflecting their ubiquity and distinctiveness to humans. The ecological dominance and conspicuous social behavior of ants have long engaged the attention of natural historians. In terms of their species diversity, relative abundance, ecological impact and social habits, ants emerge as one of the most prominent groups of arthropods.
Perhaps they also join spiders as arthropodal challenges to evolutionary theory (see 10/21/2005, 05/25/2005, 09/13/2001). Ants have complex sticky feet 09/27/2001, 06/05/2001) and navigate with intricate software (09/12/2001). We learned last year that ants are also adept hang gliders (02/09/2005), and just two months ago that they are better teachers than chimpanzees (01/11/2006). They also teach us humans the value of industry. An early natural philosopher, Solomon, advised, “Go to the ant, thou sluggard; consider her ways, and be wise, which having no guide, overseer, or ruler, provideth her meat in the summer, and gathereth her food in the harvest.” (Proverbs 6:6-8). See also Aesop.
1Philip S. Ward, “Primer: Ants,” Current Biology, Vol 16, R152-R155, 07 March 2006.
2Grimaldi and Agosti, “A formicine in New Jersey Cretaceous amber (Hymenoptera: Formicidae) and early evolution of the ants,” PNAS, published online before print November 14, 2000, 10.1073/pnas.240452097. See also our 11/14/2000 entry.
3Engel and Grimaldi, “Primitive New Ants in Cretaceous Amber from Myanmar, New Jersey, and Canada (Hymenoptera: Formicidae),” BioOne, doi: 10.1206/0003-0082(2005)485[0001:PNAICA]2.0.CO;2, American Museum Novitates: No. 3485, pp. 1�23. See also a similar find in Geologica Acta, about the oldest known ant: “Although its characters are those of modern ants, it does not fit in any recent ant subfamilies.”
If anyone can find any value whatsoever in Ward’s evolutionary speculations, please write in and explain. If you subtract the assumption that evolution is a fact, and remove the fictional diagram of millions of years, and erase the supposition that everything evolved from something else by common ancestry, the actual empirical facts speak loud and clear: ants are complex and amazing animals that appeared suddenly on earth and fulfill a variety of important roles in the ecology. Why does anyone need to be told that they evolved from stinging wasps, evolved their distinctive features several times (05/28/2003), and figured out their complex foraging and navigating skills (the envy of robotics experts) on their own? How is this speculation helping science? It serves nothing but to prop up the dead corpse of Charlie at the head of a traditional evolutionary parade. Worse, it distracts attention from the wonders of nature that should inspire us to observe, study, and think. Send your local Darwinist a gift and support an industrious entrepreneur: send Uncle Milton’s Ant Farm with a sticky-note saying, “Prov. 6:6-8.”