The giant deer Megaloceros giganteuswas a celebrated victim of the LatePleistocene megafaunal extinction, the

timing and causes of which are hotly debat-ed1. Until now, it was believed that the giantdeer’s demise occurred during the LateGlacial (about 10,600 years ago), before thePleistocene–Holocene boundary. Here wereport new radiocarbon dates from twospecimens in stratified contexts, which indi-cate that a giant deer population still existedaround the northern Irish Sea Basin in theearly Holocene — 1,400 years after theirsupposed extinction.

One of the most characteristic animalsof the Late Pleistocene European mega-fauna, the ‘Irish elk’ had a shoulder heightof 2.1 metres and an antler span of up to3.6 metres. In Ireland and the Isle of Man,most specimens are from deposits of theAllerød Interstadial, about 12,000–11,000years before present (BP)2,3. However, its dis-tribution extended across Europe to CentralAsia, and its fossil record extends back400,000 years4.

An almost complete skeleton of an adultmale giant deer was found in 1819 in marlsediments at Loughan Ruy, a basin on theBallaugh gravel fan, Isle of Man (Fig. 1a)5,6.Another nearly complete adult male skele-ton was recovered in 1887 from a marl pit atClose-y-Garey7. The Manx Museum inDouglas on the Isle of Man has this on dis-play with a fragment of antler (no. 1977-17)found in 1976 at Glen Wyllin in one of thekettle-holes exposed on the cliffs8.

We obtained radiocarbon acceleratormass spectroscopy (AMS) dates for all threespecimens: Close-y-Garey, 11,495595 yr BP

within the Allerød interstadial (Lab. no.AA-30361, d13C%4121.0); Glen Wyllin,10,780595 yr BP during the Younger Dryas(AA-30362, d13C%4121.2); and Ballaugh,9,225585 yr BP in the early Holocene (AA-29744, d13C%4120.3). The AMS dates(quoted uncalibrated) agree with the strati-graphic context of each specimen. The spec-imen from Ballaugh is the latest reported 14Cdate for giant deer anywhere in the world.Another AMS date of 9,430565 yr BP (AA-18513, d13C%4121.4) from a fragmentaryMegaloceros antler found in the River Creein southwest Scotland (specimen no. NMSZ1993.160.12) confirms the survival of thespecies into the early Holocene in this area.

Equally interesting are the very unusualsize and proportions of the Close-y-Garey,and especially the Ballaugh, skeletons.We compared their dimensions to a largesample of male M. giganteus from the IrishLate Glacial (Fig. 1b). In all postcranial and

dental dimensions, the Ballaugh skeleton isbelow the entire Irish range and more thantwo standard deviations from its mean (sig-nificant at 95% level). This indicates thatsize decreased into the Holocene. TheAllerød Close-y-Garey skeleton is some-what larger: within the Irish range on twomeasurements, below it on two others.

Whereas the Close-y-Garey skeleton hasrelatively similar proportions to the con-temporaneous Irish sample, the earlyHolocene Ballaugh animal has a very largeskull compared with its postcrania (Fig.1b). Exaggerated head-to-body size ratio iscommon in dwarfed populations of mam-mal species9. It is not clear whether thecomparatively small size of the Isle of Manspecimens is a geographical or a chrono-logical effect — the Isle of Man becameisolated from mainland Britain at about10,000 yr BP (Fig. 1a)10 .

Despite the small body size, the antlersof both skeletons are well within the Irishsize range for adult males (Fig. 1b). There isstrong intraspecific allometry among IrishM. giganteus11, with smaller animals havingrelatively shorter antlers, described byL40.00025B 2.115, where B is the basal skulllength and L is the length of the antler fromthe rose to the end of the palm. In the Bal-laugh specimen, B4468 mm, predicting anantler length of 1,110 mm; the actual value

is 1,218 mm. In the Close-y-Garey speci-men, B4450 mm, predicting a length of1,022 mm; the actual antler length is1,090 mm. Reduced display organs are pre-sumed to signify a prelude to extinctionfrom nutritional stress12, but the Ballaughand Close-y-Garey individuals show thatsexual selection maintained a relativelylarge antler size until the last documentedsurvival of the species.

Explanations for megafaunal extinctionshave generally assumed that these were pre-Holocene and invoke causes from withinthe Late Pleistocene, whether human orenvironmental. The nutrient requirementsof M. giganteus have been modelled, par-ticularly in relation to the substantial costsof growing the huge antlers13. Based on thelatest date reported, within the YoungerDryas (10,6105495 yr BP (UB-2699), fromBallybetagh, Ireland), extinction is explainedin terms of the reduced forage density duringthat episode, leading to a conflict betweensexual selection for increased body andantler size, and nutritional selection pres-sures for reducing them13.

These factors probably reduced popula-tions and possibly the body size of M.giganteus in the terminal Pleistocene, butour dating indicates that they cannothave caused its extinction. Survival ofM. giganteus in the temperate, forested

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Survival of the Irish elk into the HoloceneGiant deer on the Isle of Man around 9,000 years ago may have been the last of the line.

Close-y-Garey

Ballau

gh

Standard deviation units from Irish mean

–3 –2 –1 0 +1 +2

Antler length, n = 70

Skull length, n = 70

M3 length, n = 37

Radius length, n = 29

Metacarpal length, n = 33

Metatarsal length, n =51

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Figure 1 Localities and size comparison of Megaloceros giganteus specimens. a, Localities (stars) with giant deer remains in the Irish

Sea Basin with new radiocarbon dates. A, Ballaugh, Isle of Man; B, Glen Wyllin, Isle of Man; C, Close-y-Garey, Isle of Man; D, River Cree,

southwest Scotland. The bathymetry is also shown in metres. The North Channel has been fully open since 12,000 years BP; the shore-

line for this period corresponds roughly to the 50-m curve. The Isle of Man became isolated from mainland Britain around 10,000 radio-

carbon years BP (ref. 10). b, Size of the Ballaugh and Close-y-Garey M. giganteus skeletons in comparison with a sample from the Late

Glacial of Ireland. Squares, Irish mean; horizontal lines, Irish range; triangles and dashed line, Ballaugh skeleton (National Museums of

Scotland, specimen no. NMSZ 1820.16); circles and dotted line, Close-y-Garey skeleton (Manx Museum, no. 1900-1). Data are plotted

in units of Irish standard deviations. Measurements of the Irish comparative sample were taken from from ref. 4, except antler and skull

lengths, which were from ref. 11. Skulls with antlers are known males. Limb bones are isolated specimens but show clear bimodal size

distributions4, allowing males to be reliably separated; the third lower molar (M3) shows little or no sexual dimorphism so the total sample

was used. Antler length is direct length from the rose to the distal end of the palm; skull length is condylobasal length; M3 length is taken

at crown base lingually; limb bone lengths are the longest dimension.

© 2000 Macmillan Magazines Ltd

environment of northwestern Europe inthe early Holocene allows the possibilitythat Mesolithic hunters could have beenresponsible for the giant deer’s final demise,although the terminal dates for M. giganteuspre-date the earliest human evidence inboth the Isle of Man and Ireland14. Alter-natively, it is possible that the Holocenevegetational zonation was unlike that ofprevious interglacials and so led to thedemise of species adapted to a ‘mosaic’environment12.

It is hard to generalize about causes ofextinction as different factors may eliminatepopulations in different areas. Our newdates for Megaloceros add an important newspecies to the list of Holocene survivorsfrom the Pleistocene world. For the woollymammoth Mammuthus primigenius, thespecies most extensively dated, recent findson Wrangel Island in the Siberian Arcticindicated an unexpected survival into theHolocene15. It is possible that we are wit-nessing a pattern of terminal survival ofPleistocene megafauna on islands at themargins of continents.Silvia Gonzalez*, Andrew C. Kitchener†,Adrian M. Lister‡

*School of Biological and Earth Sciences, Liverpool John Moores University, Byrom Street,Liverpool L3 3AF, UK†Department of Geology and Zoology, National Museums of Scotland, Chambers Street,Edinburgh EH1 1JF, UK‡Department of Biology, University College London,Gower Street, London WC1E 6BT, UK e-mail: A.Lister@ucl.ac.uk1. Stuart, A. J. Biol. Rev. 66, 453–562 (1991).

2. Mitchell, G. F. & Parkes, H. M. Proc. R. Ir. Acad. 52B, 291–314

(1949).

3. Dickson, C. A., Dickson, J. H. P. & Mitchell, G. F. Phil. Trans. R.

Soc. Lond. B 258, 31–79 (1970).

4. Lister, A. M. Zool. J. Linn. Soc. 112, 65–100 (1994).

5. Hibbert, S. Edinb. J. Sci. 3, 15–28 (1825).

6. Oswald, H. R. Edinb. J. Sci. 3, 28–31 (1825).

7. Kermode, P. M. C. Geol. Mag. n.s. decade IV, 5, 116–119

(1898).

8. Reeves, G. M. Proc. IOM Nat. Hist. Antiq. Soc. n.s. VIII (no. 4,

1978–80), 416–422 (1982).

9. Lister, A. M. Geol. Soc. Spec. Publ. 96, 151–172

(1995).

10.Lambeck, K. J. Geol. Soc. Lond. 11, 437–448 (1995).

11.Gould, S. J. Evolution 28, 191–220 (1974).

12.Guthrie, R. D. in Quaternary Extinctions: A Prehistoric

Revolution (eds Martin, P. S. & Klein, R. G.) 259–298 (Univ.

Arizona Press, Tucson, 1984).

13.Moen, R. A., Pastor, J. & Cohen, Y. Evol. Ecol. Res. 1, 235–249

(1999).

14.Woodman, P. C. Br. Archaeol. Rep. no. 58 (1978).

15.Vartanyan, S. L., Garutt, V. E. & Sher, A. V. Nature 362, 337–340

(1993).

754 NATURE | VOL 405 | 15 JUNE 2000 | www.nature.com

Cell signalling

Control of free calcium in plant cell nuclei

Free calcium ions stimulate a huge vari-ety of processes inside the cell1, elicit-ing specific responses that depend on

their spatio-temporal concentrations2,3.Here we investigate how these changes incalcium concentration are triggered in thecytosol and nucleus of plant cells, and findthat they are independently controlled inthe two compartments. Our results indicatethat in plants some processes in the nucleusmay be executed in response to anautonomously regulated nuclear calciumsignal, although it is not clear whether thishappens in animal cells as well4,5.

To compare nuclear and cytosolic calci-um signals in plant cells, we used proto-plasts from transgenic tobacco plants thatconstitutively express the calcium reporteraequorin either in the cytosol6 or in thenucleus7. The agent mastoparan8 stimulatedlarge and transient increases in free calciumin both the cytosol and nucleus in a dose-dependent manner, with the maximumincrease in free-calcium concentrationbeing in the micromolar (mM) range forboth compartments.

We found, however, that the cytosol andnucleus were differentially sensitive tomastoparan, with half-maximal (in terms ofpeak height) increases in free calcium in thecytosol and nucleus being elicited by 1 µM

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1.61.41.2

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b

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Figure 1 Changes in free calcium concentration in the cytosol

and nucleus of tobacco protoplasts. Protoplasts expressing the

calcium reporter aequorin in the cytosol or in the nucleus are

referred to as ‘cyt’ or ‘nuc’, respectively. a, Time course of

changes in free calcium concentration in intact cyt (blue triangles),

intact nuc (green squares) and lysed nuc (red diamonds) proto-

plasts induced in response to 5 µM mastoparan. b, Responses of

intact cyt (trace 1), lysed cyt (trace 2) and of intact nuc (trace 3)

and lysed nuc (trace 4) protoplasts to 5 µM mastoparan. RLU, rel-

ative light unit. c, Effect on nuclear Ca2+ concentration after addi-

tion of 1 mM (trace 1) or 10 mM (trace 2) CaCl2 to the incubation

medium containing lysed nuc protoplasts. Scale bars, 10 s.

and 5 mM mastoparan, respectively (resultsnot shown). The nuclear compartmentconsistently responded later than thecytosol, regardless of mastoparan concen-tration (the delay ranged from 1352.5 s inthe presence of 0.5 µM mastoparan (notshown) to 450.5 s with 5 µM mastoparan(Fig. 1a)).

We reasoned that the different responseof the two cellular compartments to masto-poran might be due to a difference in theintracellular movement either of calciumitself or of a regulatory compound(s) fromthe cytosol to the nucleus, or to a specificand independent response by the nucleusitself. To test whether the nucleus couldmount an autonomous calcium response tomastoparan, we compared the response tomastoparan of intact protoplasts with thatof protoplasts that had been lysed undermild hypotonic-shock conditions9 so thattheir nuclei were exposed.

As expected, 5 mM mastoparan elicitedan increase in free calcium in intact proto-plasts expressing aequorin in either thecytosol or the nucleus (Fig. 1b, traces 1 and3). Only a residual response (1–3%, relativeto intact protoplasts) to mastoparan wasrecorded for the lysate prepared fromprotoplasts expressing aequorin in thecytosol (Fig. 1b, trace 2). In contrast, nuclearaequorin could still respond to mastoparan,with the size of the response being 70% ofthat by intact protoplasts (Fig. 1b, trace 4).

Under these conditions, addition of1–10 mM calcium to the lysed nuclear

preparation had no effect on the existingconcentration of free calcium (Fig. 1c), sug-gesting that the nuclear compartment is notpassively permeable to calcium, at least inthe form of isolated nuclei. The calciumresponse to mastoparan recorded fromlysed protoplasts expressing aequorin inthe nucleus was always earlier than that inthe corresponding intact protoplasts in thepresence of either 1 mM (not shown) or5 mM mastoparan (Fig. 1a).

Taken together, our results suggest thatnuclei from plant cells are capable of gener-ating their own calcium signals independent-ly of changes in calcium ion concentration inthe cytosol. Nicolas Pauly*, Marc R. Knight†, Patrice Thuleau*, Arnold H. van der Luit‡,Marc Moreau§, Anthony J. Trewavas||,Raoul Ranjeva*, Christian Mazars**Signaux et Messages Cellulaires chez les Végétaux,UMR-CNRS/UPS 5546, Pôle de BiotechnologieVégétale, 24 Chemin de Borde Rouge, BP 17Auzeville, 31326 Castanet-Tolosan, France†Department of Plant Sciences, University ofOxford, South Parks Road, Oxford OX1 3RB, UK‡Netherlands Cancer Institute, Plesmanlaan 121,1066 CX Amsterdam, The Netherlands§Centre de Biologie du Développement, UMRCNRS/UPS 5547, Université Paul Sabatier, 118

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