100-mllion-year-old amber preserves oldest animal societies

February 11, 2016
Two different ant species fighting, caught in 100-million-year old Burmese amber. Credit: © AMNH/D. Grimaldi and P. Barden

Fighting ants, giant solider termites, and foraging worker ants recently discovered in 100-million-year-old amber provide direct evidence for advanced social behavior in ancient ants and termites—two groups that are immensely successful because of their ability to organize in hierarchies. The new work, led by scientists at the American Museum of Natural History and the University of Kansas, and published today in two papers in the journal Current Biology, proves that advanced sociality in ants and termites was present tens of millions of years earlier than indicated by the previous fossil record.

"Ecologically, advanced sociality is one of the most important adaptive features for animals," said co-author Dave Grimaldi, a curator in the Museum's Division of Invertebrate Zoology. "All ants and are social, and they are ubiquitous across terrestrial landscapes, with thousands of described species and probably even more that we haven't yet found."

Advanced sociality, or eusociality, a hallmark of which is reproductive specialization into worker and queen castes, is essentially a phenomenon of the group of invertebrates known as arthropods. Queens and reproductive males take the roles as the sole reproducers while the soldiers and workers defend and care for the colony. Eusociality occurs in a range of arthropods, from some shrimp, beetles, and aphids, to various wasps, though the phenomenon is nowhere more pronounced than in honey bees, ants, and termites. (Among vertebrates, eusociality is found in just two species of African mole rats.)

Eusociality is thought to have appeared first in termites in the Late Jurassic, about 150-160 million years ago. However, before the new work, the earliest termites ever found that could definitively be tied to a caste system were from the Miocene, a mere 20 to 17 million years ago. A similar story held true for ants, whose evolutionary history with eusociality was also thought to be long, but only weakly supported by the fossil record.

A reproductive termite Krishnatermes yoddha is in amber. Credit: © AMNH/D. Grimaldi and P. Barden

"In the Cretaceous amber we examine, the ants and termites represent the earliest branches of each evolutionary tree, and the species are wildly different from what their modern relatives look like today," said co-author Phillip Barden, a recent graduate of the comparative biology doctoral program at the Museum's Richard Gilder Graduate School and a National Science Foundation Postdoctoral Fellow at Rutgers University. "We wanted to know how social these creatures were, if they were social at all."

A number of spectacular pieces of amber recently recovered from Myanmar gave Barden, Grimaldi, and their colleagues a clear answer: Eusociality was going strong in both groups during the Cretaceous.

In termites, the researchers made this determination based on the diverse anatomy of the animals, indicating the presence of castes. They found six different termite species preserved in the amber, two of which are new to science: Krishnatermes yoddha, comprising workers, reproductives, and soldiers; and Gigantotermes rex, based on one of the largest soldier termites ever found—about an inch in length, half of it being its head, with scissor-like jaws.

These reconstructions show two new genera and new species described by the researchers. On the left is the soldier caste of Gigantotermes rex (among the largest termite soldiers known, even among living species). On the right are the three castes (winged reproductive, worker, and soldier) of Krishnatermes yoddha. Credit: © AMNH/D. Grimaldi

The amber ant fossils froze a number of eusocial behaviors in time. Those include: the presence of different castes, including queen ants and workers; groups of in single pieces of amber, probably nestmates foraging together; and two workers of different ant species engaging in combat.

"We know that wingless solitary relatives of ants don't fight or defend territories against other species," Barden said. "But modern ants war all of the time. The behavior of these fossil ants, frozen for 100 million years, resolves any ambiguity regarding sociality and diversity in the earliest ."

Explore further: Worker ants paralyze and kill termites from afar

More information: Current Biology papers:

www.cell.com/current-biology/abstract/S0960-9822(16)00041-5
www.cell.com/current-biology/abstract/S0960-9822(16)00042-7

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CubicAdjunct747
4.3 / 5 (6) Feb 11, 2016
I"m so glad we can find and analyze such precious items. It really quiets the insane illogical ideas of christian science and other non evolution believers.
24volts
4.2 / 5 (5) Feb 12, 2016
I'm Christian and I have no problem with evolution. Please don't paint us all with that same 'stupid' brush.
CubicAdjunct747
not rated yet Feb 12, 2016
Speaking on terms of archeaology, then why dont you tell me about Jesus's diapers? I mean we have tons of items from ancient China that is over 5000 years old muc older than your christian god. All those items are more important to keep than anything from your god? THree kings even visited your baby god, and didnt keep anything? I would love to have Jesus' dirty diapers, its gods diapers and worth something right?
24volts
not rated yet Feb 22, 2016
His father was a carpenter. That has never been a high paying job. I'm sure what ever diapers he used -if they even used any at the time - would have been used to bits and discarded. They didn't have pampers back then and poor people didn't waste stuff. I'm not here to preach to you or explain things that happened a couple thousand years ago. I wasn't there. I don't try to preach religion to people here or anywhere else as far as that goes. All I asked YOU to do is not ASSUME that just because someone might believe in GOD they don't believe science is accurate. Don't bother answering back as I won't be reading it anyway. I automatically block people on here that don't have anything to add to the subject of the article and only try to insult others. You will just be one among a dozen or so others that will no longer troll and ruin the comments sections - at least for me anyway.
CubicAdjunct747
5 / 5 (1) Feb 25, 2016
Its ok 24 VOlts, you can block and continue to hide things that may allow you to see how the real universe works. By the way, you still didnt explain why there is nothing found leftover from jesus, diaper, spoon, something: but there are still many many things found from human civilizations that are much older, even bug civilizations and societies that are 50,000 times older than jesus. I can explain it for you, but you know the answer i think.

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