Neanderthals more like Modern Humans than we thought?

There’s an inter­est­ing press release below the fold. Examination of Neanderthal teeth sug­gests that their child­hood phase was a lot longer than pre­vi­ously thought. It is cur­rently thought that Neanderthal chil­dren grew up a lot faster than their mod­ern coun­ter­parts. A big bit of the evid­ence in favour of this is exam­in­a­tion of perikymata. These are mark­ings in teeth that show how the tooth grew, a bit like rings in tree trunks.

Previous work sug­ges­ted that Neanderthals grew up to 15% faster than mod­ern humans. Thus they reached matur­ity faster and this meant less time was neces­sary for guid­ing them to matur­ity. This is a handy thing, as evid­ence of age of death sug­gests that a Neanderthal was doing well to reach thirty. In addi­tion they were mar­tyrs to arth­ritis, so it would be an advant­age to have rap­idly grow­ing children.

However Debra Guatelli-Steinberg, an anthro­po­logy pro­fessor, at Ohio State has gone back and examined what yard­stick was used to meas­ure the Neanderthal growth against. Teaming up with aca­dem­ics from other uni­ver­sit­ies she’s examined teeth from a wide vari­ety of mod­ern people and found that Neanderthal growth actu­ally falls within a com­par­able range.

This is poten­tially very excit­ing. If Neanderthal chil­dren did take a lot of care, where did this come from? Normally you’d expect the par­ents, but in this case there’s a strong pos­sib­il­ity that the par­ents would be injured or dead, and the longer the child­hood, the more likely a child is to become an orphan while a depend­ent. We’ve ten­ded to think that life for a Neanderthal was nasty, bru­tish and short – and that they were too. Instead more and more evid­ence is sug­gest­ing that they were rather sophisticated.

I’ve now dis­covered there’s a Dental Anthropology Association. That sounds like hard work.

The press release is below.

COLUMBUS , Ohio – Recent research sug­ges­ted that ancient Neanderthals might have had an accel­er­ated child­hood com­pared to that of mod­ern humans but that seems flawed, based on a new assess­ment by research­ers from Ohio State University and the University of Newcastle .

They found that the rate of tooth growth present in the Neanderthal fossils they examined was com­par­able to that of three dif­fer­ent pop­u­la­tions of mod­ern humans.

And since the rate of tooth growth has become a more-accepted tool for estim­at­ing the length of child­hood among hom­in­ids, the find­ing is the latest evid­ence sug­gest­ing that Neanderthals may not have been as dif­fer­ent from mod­ern humans as some research­ers have thought.

The study by Debbie Guatelli-Steinberg, assist­ant pro­fessor of anthro­po­logy at Ohio State , appeared in the cur­rent issue of the Proceedings of the National Academy of Sciences. Donald J. Reid, lec­turer in oral bio­logy at the University of Newcastle , Thomas A. Bishop, asso­ci­ate pro­fessor of stat­ist­ics, and Clark Larsen, pro­fessor and chair of anthro­po­logy, both at Ohio State , were co-authors in the study.

Based on our study of the enamel of these Neanderthal teeth and other mod­ern ones, we can’t sup­port the claim that Neanderthals grew up more quickly than do mod­ern humans,” she said.

Key to this con­clu­sion are micro­scopic lines on the out­side of teeth that mark the incre­mental growth of enamel on a young tooth. Like tree rings that can gauge the age of a red­wood, these stri­ations – called perikymata – record new growth on the sur­face of the tooth.

Researchers know from earlier work that these mark­ings are present in all form­ing teeth, sig­ni­fy­ing six to 12 days of growth. By mul­tiply­ing that inter­val by the num­ber of perikymata on a tooth’s sur­face, research­ers can gauge how long it took for the tooth to mature. And that gives them an indic­a­tion of the length of an individual’s childhood.

Neanderthals, Homo neander­thalen­sis, were the dom­in­ant hom­inid inhab­it­ing most of what is now Europe and west­ern Asia . Remains have been found as far south as Iraq and as far north as Great Britain . Fossil skulls reveal the dis­tinct­ively prom­in­ent brows and miss­ing chins that set them apart from later humans.

They thrived from about 150,000 to 30,000 years ago until their lin­eage failed for as-yet unknown reas­ons. Most research­ers have argued that their life in extremely harsh, Ice Age-like envir­on­ments, coupled with their lim­ited tech­no­lo­gical skills, ulti­mately led to their demise.

In a study pub­lished last year in the journal Nature, other research­ers con­ten­ded that Neanderthal teeth took 15 per­cent less time to reach matur­ity than those in later Homo sapi­ens, sug­gest­ing to them that a Neanderthal child­hood would be shorter than our own.

But Guatelli-Steinberg’s team wanted a broader com­par­ison and there­fore com­pared the teeth from Neanderthals to those of three mod­ern pop­u­la­tions – people cur­rently liv­ing in Newcastle-upon-Tyne , U.K. ; indi­gen­ous people from south­ern Africa, and Inuit from Alaska dat­ing from 500 B.C. until the present.

We chose these three groups since they would provide a good cross-section of vari­ous pop­u­la­tions from dif­fer­ent regions of the world,” she said. “We feel that they give us some insights into the vari­ation that exists within mod­ern humans.”

For the study, the research­ers used pre­cise dental impres­sions Guatelli-Steinberg and Larsen made of 55 teeth believed to come from 30 Neanderthal indi­vidu­als. These were com­pared to 65 teeth from 17 Inuit, 134 teeth from 114 south­ern Africans and 115 teeth from as many Newcastle res­id­ents. In all cases, the research­ers tal­lied the num­ber of perikymata on the enamel sur­face of the teeth.

Guatelli-Steinberg said that the res­ults showed that the enamel form­a­tion times for the Neanderthals fell eas­ily within the range of time shown by teeth from the three mod­ern pop­u­la­tions – a con­clu­sion that did not sup­port a shorter child­hood for the Neanderthals.

Enticing though it may be, these new find­ings haven’t con­vinced the research­ers that a Neanderthal child­hood was equal to a mod­ern human’s.

The miss­ing key bit of data to show that would be evid­ence for when the first molar tooth erup­ted in the Neanderthals, and we simple have no evid­ence of when that occurred,” she said.

The length of time is import­ant, the research­ers say, because unlike all other prim­ates, humans have an exten­ded period of child­hood growth, dur­ing which brain matures both in size and through exper­i­ences. Some earlier hom­in­ids matured far more quickly than mod­ern humans.

The ques­tion is when exactly did that pat­tern of devel­op­ment evolve in the growth of humans,” she said.

Support for this research came from a grant from the Leakey Foundation and from the College of Social and Behavioral Sciences at Ohio State.


When he's not tired, fixing his car or caught in train delays, Alun Salt works part-time for the Annals of Botany weblog. His PhD was in ancient science at the University of Leicester, but he doesn't know Richard III.

1 Response

  1. September 20, 2005

    Neanderthals more like Modern Humans than we thought?

    Tooth Perikymata and The Length of a Neanderthal’s Childhood

    Alun calls our atten­tion to a press release announ­cing work by Debra Guatelli-Steinberg, an anthro­po­lo­gist at Ohio State, sug­gest­ing that Neanderthal chil­dren may have matured slower than pre­vi­ously thought. It has often been claimed that Neanderthal c…