Scientific American

115 Pages·2015·16.277 MB·English

by  Dawn Stover (ed.)

Volume 24, No. 1, Spring 2015
SPECIAL EDITION
Secrets
of Staying
Young
1 Introduction: To Your Health!
36 Slowing Age-Based Memory Loss
To improve recall of words and faces, try associating
WHY WE AGE: EVOLUTION AT WORK
them with locations. B y Shelly Fan
4 Long Live the Humans
Modern genomes and ancient mummies offer clues 38 It’s Not Dementia,
to why the life span of Homo sapiens f ar exceeds It’s Your Heart Medication
that of other primates. By Heather Pringle Why cholesterol drugs might affect memory.
By Melinda Wenner Moyer
12 Why Can’t We Live Forever?
As we grow old, our cells begin to betray us. 40 Fit Body, Fit Mind?
By Thomas Kirkwood Staying sharp into old age is not just a matter of winning
the genetic lottery. By Christopher Hertzog, Arthur F.
20 The Myth of Antioxidants
Kramer, Robert S. Wilson and Ulman Lindenberger
The idea that oxidative damage causes aging and that
vitamins might preserve our youth is now in doubt. 48 Why Exercise Works Magic
By Melinda Wenner Moyer Being active is good for us for many reasons beyond
the old familiar ones. By Shari S. Bassuk,
26 Why Women Live Longer
Timothy S. Church and JoAnn E. Manson
Stress alone does not explain the longevity gap.
By Thomas Kirkwood 54 Killer Chairs
Standing more could lower risk for obesity, illness and
28 The Evolution of Grandparents
death, studies suggest. B y James Levine
Tinh teh rei sseu occf essesn oiof ro cuirt iszpeencsi ems.a B y yh aRvaec hpelal yCeads paa briig role 56 IInst eFramsitttienngt f aGstoinogd m foigrh tY imoup?ro ve health, at least mages (runners)
34 HMOeWm ToOr yS TiAnY O SMldA ARTg AeN: ND oSTt RaO LNoGst Cause 58 aMccoorrdtainlg T toh roesuegarhcths i n animals. B y David Stipp MENS Getty I
Researchers have found ways to lessen age-related Thinking about death can ease our angst and make us N SIE
DA
forgetfulness. By Hal Arkowitz and Scott O. Lilienfeld better people, too. By Michael W. Wiederman OR
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26 40 86 A
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PROSPECTS FOR TREATMENT 94 Seeds of Dementia N
66 Alzheimer’s: Forestalling the Darkness A chain reaction of toxic proteins may help explain G
Intervening before symptoms appear could be key to Alzheimer’s, Parkinson’s and other killers —and could
combating the leading cause of dementia. By Gary Stix suggest new treatment options.
74 Scanning for Alzheimer’s By Lary C. Walker and Mathias Jucker Y
A new test can identify the disorder’s early stages. 100 The Oldest Old O
How will it help patients? By Ingfei Chen People in their late 90s or older are often healthier and U
76 The Regenerating Brain more robust than those 20 years younger. Traditional N
Stem cell therapy is emerging as a promising treatment views of aging may need rethinking. B y Thomas T. Perls
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for Parkinson’s disease. By Lydia Denworth 106 If Humans Were Built to Last
84 Never Too Old for Chemo? We would look a lot diff erent if evolution had designed
As the number of patients with cancer soars, research- the human body to work well for a century or more.
ers explore how best to treat them. By Claudia Wallis By S. Jay Olshansky, Bruce A. Carnes and Robert N. Butler
112 Which Creatures Live the Longest?
CLUES TO SLOWING AGING The key indicator for animals may be total energy
86 A New Path to Longevity expended over a lifetime. By Fred Guterl
mages (runners) Sthcaietn rteitsatsrd hsa avgei unng.c oDvreurgesd t ahna ta tnwceieankte dm ietc choaunlids mw ell Articles in this special issue are updated from previous issues
NS Getty I postpone diseases of old age. B y David Stipp of Scientifi c American and Scientifi c American Mind.
ME Scientifi c American Special (ISSN 1936-1513), Volume 24, Number 1, Spring 2015, published by Scientifi c American, a division of Nature America, Inc., 75 Varick Street, 9th Floor, New York, NY 10013-1917. Canadian
N SIE BN No. 127387652RT; TVQ1218059275 TQ0001. To purchase additional quantities: U.S., $13.95 each; elsewhere, $17.95 each. Send payment to Scientifi c American Back Issues, 75 Varick Street, 9th Floor, New York,
DA NY 10013-1917. Inquiries: fax [phone] or telephone [phone]. Printed in U.S.A.
OR Copyright © 2015 Scientifi c American, a division of Nature America, Inc. All rights reserved.
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Secrets of Staying Young
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PRESIDENT de cades. Investigators are studying this group in the hope of fi nding helpful insights for
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EXECUTIVE VICE PRESIDENT the general population.
Michael Florek Can we live forever? Not likely. But as British aging expert Thomas Kirkwood writes in I
VICE PRESIDENT AND ASSOCIATE PUBLISHER,
MARKETING AND BUSINESS DEVELOPMENT “Why Can’t We Live Forever?” (page 12), science provides an abundance of clues about how N
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DIRECTOR, INTEGRATED MEDIA SALES we can live longer and, more important, stave off infi rmities for as long as possible. G
Stan Schmidt Exercise is proving to be a key factor, as several authors in this collection emphasize.
ASSOCIATE VICE PRESIDENT, BUSINESS DEVELOPMENT
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OGRAPH BY GETTY IMAGES;SEBASTIEN FEVAL Getty Images (Marchand);MERICAN IS A TRADEMARK OF SCIENTIFIC AMERICAN, INC., USED WITH PERMISSI MDSPMAAIRRAASRLOCEESERKSPCOMSNOSKAEROT STIREDNLOOEOOECITPE-ELNTNMRSCIROIVINAIGN J I,OORAEO ORTIaG EELNADMANETR yOP MNRT TMI CMRA IOCPEEEDNBAOECIRS MRRENNPS RTaEeTCNRNREhE EKiIEAt MUrCScDSNZA NGvEhMrRMTfUEShTAITTaioTRCeRTRe sAMIAMIaN AsOOyHAEalNMtrTNyTrC,AEATiaiy NMG IDAndnAERnMOVGTR A DN GLEIJPOee EK MERRZVLRyuR AEaR E CSR,E KABDORsieSET GACnt DnMhREXa IIturDaRLTEgGNRKk aEEkaROiseUBVaIaG aCESes Tn sDRlCIT cUonr AMn CieMt ITniRhTnNEeLaaeyA A M IeDiC vGd lV NcSNC lOAEiEA l kADcdAoV SNrOSG hrIGE uwcESRATrRELuEREhzoGiORDRiVmCb-reSyEI PITpNLRCeeoMoOo AaE r nERSTrcNO dekTR p(o(dtaomdp phsnwaeao aaerm gsnAWryimggcene aeei am 3teaic gmle3r6no6nleeor8 6u )ec tv er.)h feaip et.r axnI nealonwnpTnveslimt lidhne ersaitois o egoy ittft pnrPne?fem iueaa gcrassL rl ehg a riD( ft akesetnpocii atnciiaanpr7n’vqlsd s4gelg siduee de )s holen.sde e n5of,tSsstTr oe8p’y sstusfhcci)t e ogspo.etued rtisEepfnysnir srs vetgogioiteahesnonta narsra,aovyg esf ytnbediun e ncesddwe lelntg,xaca ew ioatp naegyahaus wue darwcei lr “sts dksaoiMeaet m lalfoso ytsi o nth mlsnfiehotrrn gyn rtetewet eoat“thsd AAiao lhcenias lt ocT z alg Ngcdionhdh inh rewrntweioieaueawigpu snimmbga-te grcP theg efphehoeate rrlel tlasto-taa’dssshrttontt,e e ” e iacdattmll od,aboigani vnsn tet y dLepehec sp oadaerooaecossflffn u anl fehycsgedgon cdee cebhrehacs atvguea.esso l iemfetts rStlohhat soycif(re ing”iup aweemce it(lt raasnonaps ,otng t tyyeha dhreiM m ssagy emetst7p eoni p sd6cc a( p8 Ditohep r )aakoi6.eleaaeral eml) pseMwrueag . aollsebtlw noaiihW u ofra3 rroeeSr u ep4.b r .lt totWel pkor ri avoviaevvinnieecuaeieenrdklgsrrr-,, NG
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S
E
C O N A SUNDAY MORNING IN A DECAYING AND DANGEROUS INNER-CITY BARRIO IN
R Lima, Peru, an unmarked white van carrying nearly a dozen bodies
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rumbles to a stop on the grounds of the National Institute of Neuro-
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logical Sciences. Seated in a small waiting area to the rear of the build-
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ing, a throng of well-dressed researchers and government offi cials
watches intently. As the driver clambers out, an assistant hustles off
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in search of a hospital gurney. Within minutes, two men wheel the
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fi rst body into the institute’s imaging unit.
Onlooker Caleb Finch, a biologist at the University of South- greatly extended human life over the past 200 years. But critical
S ern California, has been waiting for this moment for months. as they were to extending human life, they are only part of the
T Tall, gaunt and graying, with a Father Time–style beard, the longevity puzzle, Finch warrants. Marshaling data from fi elds as
75-year-old scientist has devoted his career to the study of hu - diverse as physical anthropology, primatology, genetics and med-
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man aging. Our kind is remarkably long-lived compared with icine, he now proposes a controversial new hypothesis: that the
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other primates. Our nearest surviving relatives, the chimpan- trend toward slower aging and longer lives began much, much
I zees, have a life expectancy at birth of about 13 years. In con- earlier, as our human ancestors evolved an increasingly powerful
N trast, babies born in the U.S. in 2009 possessed a life expectancy defense system to fi ght off the many pathogens and irritants in
at birth of 78.5 years. Finch has come to Lima to fi nd out why— ancient environments. If Finch is right, future research on the
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by peering into the distant past. The cadavers in the van belong complex links among infection, host defense and the chronic dis-
to men, women and children who perished along this stretch of eases of the elderly may revolutionize scientists’ understanding
Y coastal desert as much as 1,800 years ago, long before the Span- of aging and how to cope with the challenges it brings.
O ish conquest. Cocooned in dusty textiles and interred in arid
U desert tombs, their naturally mummifi ed bodies preserve criti- AND MANY MORE
cal new clues to the mystery of human longevity. As envoys from HINTS THAT MODERN HEALTH practices might not be solely responsi-
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an era long before modern health care, they will off er case stud- ble for our long life span have come from studies of contemporary
G ies of aging in the past. Finch walks over to the van, grinning as hunter-gatherer groups. In 1985 Nicholas Blurton-Jones, a biolog-
he surveys the cargo. “That’s a pack of mummies,” he says. ical anthropologist at the University of California, Los Angeles,
Most researchers chalk up our supersized life span to the ad- set off by Land Rover across the trackless bush in Tanzania’s Lake
vent of vaccines, antibiotics and other medical advances, the de- Eyasi basin. With fi eld assistant Gudo Mahiya, Blurton-Jones
velopment of effi cient urban sanitation systems, and the avail- traveled to the isolated camps of the Hadza, hunter-gatherers
ability of fresh, nutritious vegetables and fruit year-round. In - who lived much as their ancestors had, hunting baboons and wil-
deed, much demographic evidence shows that these factors debeest, digging starchy tubers and collecting honey during the
IN BRIEF
Humans live far longer than other primates, a phe- But new research suggests that although these fac- As human ancestors ate more meat, they evolved de-
nomenon that has traditionally been credited to mod- tors have extended human life span over the past fenses against its attendant pathogens. These defenses
ern medicine, food availability and sanitation systems. 200 years, the trend actually began far earlier than that. contribute to longevity but foster disease later in life.
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Medical imaging of ancient mummies such as Egyptian scribe Hatiay has revealed clogged arteries, suggesting that cardiovascular
D ( CT scan ) disease is not a modern affl iction but rather the price humans pay for having a supercharged immune system. NG
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HERLA
NDA SUT rfraoinmy osneea scoanm pfr toom a nhoitvheesr , othf et htwe oA rfersiceaanrc hheorns ecyoblleeec.t eJdo ubranseicy idneg- tMhaehy iryaar edliys csoovuegrhedt ,o tuhte mHeaddizcaa le cnajorey.e Yde mt ausc hB lluorntgoenr- Jloivneess t hanand
OF M. LI mographic data, checking each Hadza household and recording chimpanzees did. Indeed, the Hadza had a life expectancy at
OURTESY tchene snuasm inefso arnmda atigoens osifx t htiem inesh ianb itthaen 1ts5.  yTehaerns tthhaet p faoilrlo uwpedda,t endo ttihnigs bexirptehc to ft o3 2li.v7e y e4a0r sm. oArned y eifa trhs,e ny eraeralcyh tehdr eaed tuilmtheoso ldo,n tgheery t hcoaunl da
my ); C down the names of all who had died and the causes of their death. chimpanzee reaching adulthood. Some Hadza elders survived
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OTO AP Photo (mu Ithne a THdhdaeid tziHoan af,rd oBzmlau rtlwtiovone -doJt—ohnaeerss r eoasnbetcaaireincnheted r hsso.ummea nesa rlaienrd c ecnhsiums pdaantaz eoens imnetodM itcoharele ioarnv 8ed0r ,ts et.h cChel neHaoarlodlygz,a itc hwaele iarrde r vnealonattc aievlsoe.lnye .l oInn g2 0li0v7e st woow aedn tlhitrtolpe otlo-
MIYAM did—in a natural environment teeming with pathogens and ogists, Michael Gurven of U.C. Santa Barbara and Hillard Kap-
HAEL parasites. They lacked running water and sewage systems, def- lan of the University of New Mexico analyzed data from all fi ve
MIC ecating in a zone 20 to 40 meters away from their camps, and modern hunter-gatherer societies that researchers had studied
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SCIENTIFIC AMERICAN
demographically. Infections counted for 72 percent of the deaths, search in Uganda shows that animal fat constitutes only 2.5 per-
and each group revealed a very similar J-shaped mortality curve— cent of their yearly fare by dry weight.
with child mortality as high as 30 percent, low death rates in In all likelihood, Finch says, the earliest members of the hu-
early adulthood and exponentially rising mortality after the age man family consumed a similar plant-based diet. Yet sometime
of 40. Then Gurven and Kaplan compared these curves with between 3.4 million and 2.5 million years ago, our ancestors in-
those of both wild and captive chimpanzees: the simians experi- corporated a major new source of animal protein. As sites in Ethi-
enced the sharp uptick of adult mortality at least 10 years earlier opia show, they began butchering the remains of large, hoofed
than human hunter-gatherers. “It appears that chimpanzees mammals such as antelopes with simple stone tools, smashing
age much faster than humans,” concluded Gurven and Kaplan the bones to get at the fat-rich marrow, slicing off strips of meat,
in their paper detailing the fi ndings, “and die earlier, even in and leaving behind telltale cut marks on femurs and ribs. And by
protected environments.” 1.8 million years ago, if not earlier, humans began actively hunt-
Yet when, exactly, did humans begin living longer? To obtain ing large game and bringing entire carcasses back to camp. The
clues, anthropologists Rachel Caspari of Central Michigan Uni- new abundance of calories and protein most likely helped to fuel
versity and Sang-Hee Lee of U.C. Riverside examined the re- brain growth but also increased exposure to infections. Finch
mains of 768 individuals from four ancestral human groups suggests that this risk favored the rise and spread of adaptations
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spanning millions of years. By assessing the degree of dental that allowed our predecessors to survive attacks by pathogens
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wear, which accumulates at a constant pace from chewing, they and thus live longer.
C estimated the ratio of young adults around 15 years of age to old- The trend toward increasing carnivory would have exposed
R er adults around age 30 (old enough to be a grandparent) in each our ancestors to pathogens in several ways. Early humans who
of the four groups. Their studies revealed that living to 30 and scavenged the carcasses of dead animals, and who dined on raw
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beyond became common only recently in our prehistoric past. meat and viscera, boosted their chances of ingesting infectious
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Among the australopithecines, which emerged in Africa around pathogens. Moreover, as humans took up hunting large animals,
S 4.4 million years ago, most individuals died before their 30th they faced greater risks of lacerations and fractured bones when
birthday. Moreover, the ratio of thirtysomethings to 15-year-olds closing in on their prey: such injuries could lead to deadly infec-
was just 0.12. In contrast, Homo sapiens who roamed Europe be- tions. Even cookery, which may have emerged as early as one mil-
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tween 44,000 and 10,000 years ago often lived to 30 or more, lion years ago, if not earlier, posed perils. Inhaling wood smoke
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achieving a ratio of 2.08 [see “The Evolution of Grandparents,” daily exposes humans to high levels of endotoxins and soot parti-
by Rachel Caspari, on page 28]. cles. Roasting and charring meat improves both the taste and di-
Calculating the life expectancy of early H. sapiens p opula- gestibility but creates chemical modifi cations known as advanced
tions is challenging, however: detailed demographic data, such glycation end products, which contribute to serious diseases such
S as those supplied by both census records and death registra- as diabetes. Our ancestors’ later embrace of agriculture and ani-
T tions, are lacking for much of our long past. So Finch and his mal husbandry, which began some 11,500 years ago, added new
colleague Eileen Crimmins, a gerontologist at the University of dangers. The daily proximity of humans to domesticated goats,
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Southern California, analyzed the earliest, virtually complete sheep, pigs, cattle and chickens, for example, elevated the risk of
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statistical set of that nature available—data fi rst gathered in contracting bacterial and viral infections from animals. More-
I Sweden in 1751, decades before the advent of modern medicine over, as families settled permanently in villages, sewage from hu-
N and hygiene. The study revealed that mid-18th-century Swedes mans and livestock contaminated local water supplies. Pathogen-
had a life expectancy at birth of 35. But those who survived bac- ic bacteria thrived.
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terial infections and contagious diseases such as smallpox dur- Even so, humans exposed to such health risks in 1751 in Swe-
ing childhood and reached the age of 20 could reasonably look den lived longer than their simian relatives. To tease out clues to
Y forward to another 40 years. this longevity, Finch began studying the scientifi c literature on
O To Finch, these fi ndings raised a major question. The 18th- chimpanzee and human genomes. Previously published studies
century Swedes lived cheek by jowl in large, permanent villages, by others showed that the two genomes were around 99 percent
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towns and cities, where they were exposed to serious health risks identical. But in the uniquely human 1 percent, evolutionary biol-
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unknown to small communities of mobile chimpanzees. So why ogist Hernán Dopazo, then at the Prince Felipe Research Center
G did the Swedes live longer? The answer, it turns out, may lie in the in Valencia, Spain, and his colleagues discerned a disproportion-
meaty diets of their early human ancestors and the evolution of ately high number of genes that had undergone positive selection
genes that protected them from the many hazards of carnivory. and that played key roles in host defense and immunity—specifi -
cally in a part of the defense system known as the infl ammatory
MEAT-EATING GENES response. Positive selection favors genes that hone our ability to
CHIMPANZEES SPEND most of their waking hours in a sweet pur- survive and reproduce, which allows them to become more fre-
suit: foraging for fi gs and other ripe fruits. In search of fructose- quent in populations over time, a process that leaves a distinctive
rich fare, they range over large territories, only occasionally us- “signature” in the DNA sequence. Dopazo’s fi ndings added new
ing the same night nest twice in a row. They are skilled at hunt- weight to an idea growing in Finch’s mind. He wondered if natu-
ing small mammals such as the red colobus monkey, but they do ral selection had endowed ancient humans with a souped-up sys-
not deliberately set out searching for these prey. Nor do they tem for fi ghting off the microbial threats and warding off other
consume large quantities of meat. Primatologists studying wild health hazards posed by increased meat consumption, thereby
chimpanzees in Tanzania have calculated that meat makes up extending our life span.
5 percent or less of the simians’ annual diet there, whereas re- In the war against bacteria, viruses and other microbes that
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seek to invade our tissues, the human host defense system Even today children who carry A POE e4 enjoy an advantage
brandishes two powerful weapons: the innate immune system over those who do not. In one study of youngsters from impov-
and the adaptive immune system. The innate system is the fi rst erished families living in a Brazilian shantytown, APOE e4 carri-
responder. It mobilizes immediately at the scene of an attack or ers succumbed to fewer bouts of diarrheal disease brought on
injury to eliminate pathogens and heal damaged tissue, and it by Escherichia coli o r Giardia infections than noncarriers did.
essentially responds in the same way to all threats. The adap- And they scored higher on cognitive tests, most likely as a result
tive system, in contrast, kicks into gear more slowly, customiz- of their greater absorption of cholesterol—a dietary require-
ing its response to particular pathogens. In doing so, it creates ment for neurons to develop in the brain. “So this would have
an immunological memory that confers lifelong protection been adaptive, we think,” Finch remarks.
against the invader.
The infl ammatory response is part of the innate immune sys- A DEFERRED COST
tem. It goes to work when tissues suff er damage from microbes, ALL TOLD, APOE e4 seems to be a key part of the puzzle of hu-
traumatic wounds, injuries or toxins, and, as Finch points out, man longevity. Ironically, now that we live longer, this gene
physicians have long recognized its hallmarks. Some 2,000 years variant appears to double-cross us later in life. Its debilitating
ago Aulus Cornelius Celsus, a Roman medical author, described eff ectsbecame apparent only as our human ancestors increas-
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four cardinal signs of infl ammation—heat, redness, swelling and ingly survived to middle age and beyond. In Lima, Finch and an
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pain. The heat and redness come from a swift international team of cardiologists, radiolo-
and marked increase in the fl ow of warm blood EIGHTEENTH- gists, biologists and anthropologists are C
to the damaged tissue. Swelling then results CENTURY SWEDES searching for traces of these affl ictions in the R
from increased vascular permeability, which preserved cardiovascular tissues of ancient
LIVED CHEEK BY E
causes blood cells and plasma to leak into the adult mummies.
aff ected area, carrying proteins that can assist JOWL IN LARGE, Inside the crowded imaging unit in Lima, T
in preventing the spread of infection and in ini- PERMA NENT Finch hoversover a technician’s computer. It S
tiating wound healing. has been a long, trying morning. Several of the
VILLAGES, TOWNS
Finch began examining the human-specifi c mummy bundles transported to the unit are
AND CITIES, WHERE O
changes in genes related to host defense. He too large to fi t into the CT scanner. Others,
was quickly struck by the changes that had af- THEY WERE when scanned, reveal little more than skeletal F
fected the a polipoprotein E ( APOE ) gene. This EXPOSED TO remains, raising doubts that the preservation
important gene strongly infl uences the trans- SERIOUS HEALTH of human tissue in the bundles will be ade-
port and metabolism of lipids, the develop- quate for the study.
RISKS UNKNOWN
ment of the brain and the workings of the im- But no one is giving up. On the screen is a S
mune system. It has three primary, uniquely TO SMALL crisp, three-dimensional CT scan of a bundle T
human variants (alleles), of which APOE e4 COMMUNITIES just wheeled in from the van. Hunching for-
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and APOE e3 are the most prevalent. OF MOBILE ward, cardiologists Gregory Thomas of Long
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APOE e4’ s DNA sequences closely resem- Beach Memorial Medical Center in California
CHIMPANZEES.
ble those in chimpanzee APOE, strongly sug- and Randall C. Thompson of the University of I
SO WHY DID
gesting that it is the ancestral human variant Missouri School of Medicine–Kansas City N
that emerged near the beginning of the Homo THE SWEDES scrutinize an anatomical landscape rendered
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genus more than two million years ago and LIVE LONGER? strangely foreign by centuries of decay and
thus may have had the earliest eff ect on our desiccation. As the technician scrolls up and
longevity. Diff ering in several critical amino down the image, the two cardiologists gradu- Y
acids from the chimp version, APOE e4 vigorously ramps up ally pick out preserved soft tissue and the snaking trails of ma- O
the acute phase of infl ammation. It boosts the production of jor arteries. The relief in the room is palpable. Then, unable to
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proteins such as interleukin-6, which helps to increase body resist, the two cardiologists take a quick preliminary look along
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temperature, and tumor necrosis factor–alpha, which induces the arteries for small, dense, white patches—calcifi ed plaque
fever and inhibits viruses from replicating. Equipped with this that signals an advanced stage of atherosclerosis, or hardening G
supercharged defense system, children in ancient human fami- of the arteries, the leading cause of fatal heart attacks and
lies had a better chance of fi ghting off harmful microbes that strokes. The individual has clearly calcifi ed arteries.
they unwittingly ingested in food and encountered in their sur- Cardiologists have traditionally regarded atherosclerosis as
roundings. “When humans left the canopy and went out onto a disease of modern civilization. Contemporary behaviors such
the savanna,” Finch notes, “they had a much higher exposure to as smoking cigarettes, eschewing exercise, dining on high-calo-
infectious stimuli. The savanna is knee-deep in herbivore dung, rie diets and packing on the pounds are all known to increase
and humans were out there in bare feet.” the risk of this disease. Moreover, several recent studies point to
Moreover, early humans who carried APOE e4 most likely an emerging atherosclerosis epidemic in the developing world,
profi ted in another key way. This variant facilitates both the in- as societies there grow more affl uent and increasingly embrace
testinal absorption of lipids and the effi cient storage of fat in a modern, Western lifestyle. Yet in 2010 Thomas and a group of
body tissue. During times when game was scarce and hunting his colleagues decided to test the idea that atherosclerosis is a
poor, early APOE e4 carriers could draw on this banked fat, up- disease of modern, affl uent life by taking CT scans of ancient
ping the odds of their survival. human mummies and examining their arteries.
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SCIENTIFIC AMERICAN
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Modern hunter-gatherers such as the Hadza of Tanzania live in natural environments fi lled with parasites and pathogens,
I just as chimpanzees do. Yet they live far longer than chimps—perhaps because of genes that adapted humans to eating meat.
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The team started in Egypt, with 52 mummies dating between tuberculosis and schistosomiasis (an ailment caused by tiny par-
3,500 and 2,000 years ago. Biological anthropologist Muham- asitic worms found in contaminated water). APOE e4 carriers,
Y mad Al-Tohamy Soliman of the National Research Center in Giza with their enhanced immune systems, tended to survive many
O estimated the age at death for each individual, based on an exam- childhood infections. But they experienced decades’ worth of
ination of dental and skeletal development. Then the medical chronic high levels of infl ammation in the pathogen-rich envi-
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team pored over the scans. Discussing the images during weekly ronment—levels that are now linked to several deadly diseases of
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Skype calls, they identifi ed cardiovascular tissue in nearly 85 per- old age, including atherosclerosis and Alzheimer’s. Indeed, the
G cent of the mummies. To their surprise, 45 percent of these had arterial plaques that characterize atherosclerosis seem to accu-
defi nite or probable atherosclerosis—clear evidence that one an- mulate during infl ammation and wound healing in the vascular
cient population suff ered from the disease. “We were [also] a bit wall. “And while it might be pushing it to say the senile plaques of
surprised by just how much atherosclerosis we found in ancient Alzheimer’s are some form of scab, like the plaques on artery ves-
Egyptians who were young,” recalls team member James Suther- sels, they have many of the same components,” Finch suggests.
land, a radiologist at the South Coast Radiological Medical Group Thomas and his colleagues asked Finch to join their team.
in Laguna Hills, Calif. “The average age of death was around 40.” Together they decided to gather more data, examining the car-
When their paper came out in the Journal of the American diovascular tissues of ancient mummies from a wide range of
College of Cardiology in the spring of 2011, Finch contacted the cultures. The Egyptians in their fi rst study likely came from af-
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