Big Sur’s rugged mountains, crashing surf, and abundant wildlife have captivated generations of visitors. But the region has also attracted scientists bent on understanding this remarkable biological melting pot, where plants and animals from dramatically different ecosystems often mingle side by side. One biologist who has taken a close look is Paul Henson, who lived in the region in the 1980s and, with Don Usner, wrote The Natural History of Big Sur (University of California Press, 1996).

Big Sur attracts scientists due to its status as a biological melting pot. In no other part of the world do fog-loving coastal redwoods thrive on one slope of a canyon while arid-climate yuccas grow on the other, the book notes. Similarly, sea otters and cormorants live near dry-climate creatures like canyon wrens and whiptail lizards.

Henson, who now works for the U.S. Fish and Wildlife Service overseeing biological studies in Hawaii and other Pacific Islands, spoke with NATURE about Big Sur’s remarkable diversity.

How did you come to write this book?

I earned my undergraduate degree at the University of California, Santa Cruz, and did a lot of work at a university reserve called Big Creek that covers a big chunk of the Big Sur coast. Then, in the mid-1980s, I got a job doing sea otter research. During my down time, we started on the natural history guide. We realized that there was lots of good information floating around, but it hadn’t been consolidated in one place, and made accessible to scientists and understandable to regular readers. So we decided to do it.

Big Sur attracts scientists due to its status as a biological melting pot.

What makes Big Sur unusual?

For lack of a better term, it represents a kind of harmonic convergence of different ecological zones. It’s where the north meets the south, for instance. What’s called the Oregonia province to the north meets the Californian province to the south. So you have redwood trees meeting cacti and intermingling. You have northern and southern species of marine alga. One minute, you are hiking along in a wet cool canyon, and all of a sudden there will be a cactus. One minute it smells like Oregon and the next it smells like Mexico.

The geology plays are role, right?

The geology and topography forms the basis for it all, and it has driven geologists crazy for years. It’s incredibly jumbled and complicated. You have all these faults and slices of rock that have moved over time. And then on top of that you have a very interesting climate. Big Sur has a Mediterranean climate, which it shares with just four or five other areas in the world. It’s a climate that is extremely conducive to a lot of plants doing well. Taken together, those things make it one of the most ecologically fascinating and diverse areas in North America.

Big Sur is one of the most ecologically diverse areas in North America. Big Sur has its share of rare species …

Yes. In the 1800s, it attracted a lot of famous botanists because there are plants there that grow nowhere else. The Santa Lucia mountains have a lot of unique species because, at times, that area has been an island. So plants and animals that lived there have been cut off from other populations and evolved in their own direction. Probably the most famous species is the Santa Lucia fir tree, which is found in just a few canyons and nowhere else in the world. It looks like a tree in a Dr. Seuss book — the top droops over and it has these interesting cones.

Do you have a favorite spot in Big Sur?

Probably the Little Sur River Valley in the Ventana Wilderness. It has such a great combination of giant redwood trees and really dry chaparral. It’s one of those places where you have very different ecosystems within spitting distance of each other.

How about a favorite animal?

Probably golden eagles. The raptor [bird of prey] populations there are amazing. There are places where you can sit on a hillside, look out, and see five or six different raptors in a minute — golden eagles, red shouldered hawks, kites, red tailed hawks, kestrels. It’s a great show.

“Biologists have described something like half a dozen new species or varieties of lemurs in the last couple of years alone,” reports Conservation International’s Lee Hannah, who oversees the group’s conservation programs in Africa. One of them, a bamboo-eating lemur, has astounded researchers because it eats huge quantities of the giant grass, which is naturally laced with toxic cyanide. “It eats enough cyanide each day to kill a human several times over, but obviously has adapted to cope with that,” he says.

Mohamed Bakarr, Hannah’s colleague, notes that the bamboo-eating lemur is just one of Madagascar’s “endemic species,” or unique residents. More than 75 percent of the nation’s 836 known mammal, bird, reptile, and amphibian species are exclusively residents of the island. They include the endangered Plowshare tortoise, the world’s rarest, and the recently rediscovered Madagascar Serpent eagle, believed extinct for 60 years. Huge numbers of plants are also unique. The island, for instance, boasts seven kinds of umbrella-like baobob trees; only one type is found in the rest of Africa.

How many of these species will still be on the island in 20 years, however, is an increasingly worrisome question. Since humans first arrived on Madagascar about 2,000 years ago, they have cleared up to 90 percent of the island’s forests for logging or agriculture and grazing land. Along with the trees, at least a dozen species of lemurs have also disappeared, according to researchers at the Duke University Primate Center.

Among the extinct species was the largest lemur species ever known, a giant that weighed as much as 400 pounds and may have stood as tall as a gorilla. Other lost lemurs apparently traveled like South American sloths or Australian koalas, clinging to trees with long claws or hanging upside down from branches.

In an effort to prevent more lemurs from disappearing, Conservation International and other groups are scrambling to set up protected areas that both the Malagasy government and the nation’s 12 million people can rally around. But conservation “is a challenge in a country with such severe economic problems,” Hannah says. “If you come in and say you are interested only in lemurs, people lose interest pretty fast. That’s why we have such a strong emphasis on linking conservation to economic development activities.”

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Television Credits

A Production of Genesis Film Productions in association with Thirteen/WNET New York and Channel 4 (UK)

We recommend these Web sites for those interested in the subjects shown on the program. All links are valid as of June 9, 2000.

The Kinsey Institute for Research in Sex, Gender, and Reproduction
http://www.indiana.edu/~kinsey/
The Kinsey Institute Web site supports interdisciplinary research and the study of human sexuality.

The Naked Mole-Rat Burrow
http://nationalzoo.si.edu/animals/webcams/
Check out pictures from a live Web cam in a mole rat burrow and other detailed, interesting information from the National Zoo.

Naked Mole-Rat
http://www-personal.umich.edu/~cberger/syllabusfolder/animaldiversity/Heterocephalus_glaber.html
A species profile from the University of Michigan’s Animal Diversity Web.

Patagonian Mara
http://www.pbs.org/edens/patagonia/steppanm.htmm
Information on this rabbit-like creature from “The Living Edens: Patagonia.”

Introduction to the Bacteria
http://www.ucmp.berkeley.edu/bacteria/bacteria.html
Find out about the most common organisms on earth from the University of California. Bird

Bacteria Cam: Growth of Streptococcus Pneumoniae
http://www.cellsalive.com/cam0.htm
Watch them multiply at this site from Cells Alive!

The Australian Brush Turkey
http://www.amonline.net.au/factsheets/brush_turkey.htm
Get the lowdown on these mound builders from Australia Museum Online.

Unisexual Whiptailed Lizards
http://www.amnh.org/exhibitions/expeditions/treasure_fossil/Treasures/Unisexual_Whiptail_Lizards/lizards.html?50
Information from American Museum of Natural History.

The Redback Spider Insect
http://www.qmuseum.qld.gov.au/nature/arachnids/theredback.html
Pictures, links, and more from Australia’s Queensland museum.

Of Course Size Matters: Pheasant Hens Prefer Cocks with Bigger Spurs
http://www.teorekol.lu.se/ekol_inst/mol_ekol/faswww/faseng.htm
A study of pheasant sexual selection from Lund University.

Sex and Reproduction
http://www.mhhe.com/biosci/genbio/biolink/student/olc2/chapterindex56.htm
A textbook overview from McGraw-Hill Higher Education.

Animal Behavior Society
http://www.animalbehavior.org/ABS/
Links and more from this scientific society.

Chimpanzees and Bonobos
http://www.panda.org/resources/factsheets/species/fct_chimp.htm
Fact sheets from the World Wildlife Fund.

Print Resources

Alcock, John. ANIMAL BEHAVIOR: AN EVOLUTIONARY APPROACH. New York: Sinauer, 1997.

Bagemihl, Bruce. BIOLOGICAL EXUBERANCE: ANIMAL HOMOSEXUALITY AND NATURAL DIVERSITY. New York: St. Martins Press, 1999.

Bennet, Nigel C. AFRICAN MOLE-RATS: ECOLOGY AND EUSOCIALITY. London: Cambridge University Press, 2000.

Daly, Martin. SEX, EVOLUTION AND BEHAVIOR: ADAPTATIONS FOR REPRODUCTION. Washington: Prindle Weber, 1983.

De Waal, Frans. CHIMPANZEE POLITICS: POWER AND SEX AMONG APES. Baltimore: Johns Hopkins University Press, 1989.

Fleisher, Paul. LIFE CYCLES OF A DOZEN DIVERSE CREATURES. New York: Millbrook Press, 1996.

Solomon, Nancy G. COOPERATIVE BREEDING IN MAMMALS. London: Cambridge University Press, 1996.

Spomer, Ron. THE RUT: THE SPECTACULAR FALL RITUAL OF NORTH AMERICAN HORNED AND ANTLERED ANIMALS. San Francisco: Willow Creek Press, 1996.

Stockley, Corinne. ANIMAL BEHAVIOR. New York: EDC Publications, 1992.

Nobody knows exactly what these proto-human societies were like. But we can gather some hints from still-living relatives, such as chimpanzees. Like humans, they live in family groups. And, like humans, they can spend years nurturing a newborn to maturity. But when it comes to sex, there are some key differences. Most importantly, female chimps mate just every few years, when they are fertile, a fact they widely advertise to males with bright red genitalia. Attracted and aroused by the sight, male chimps will crowd around the female, competing to copulate as often as possible. In contrast, it isn’t obvious to men when women are fertile.

This change may have helped forge closer bonds between women and their male partners — cooperation that may have been key to successfully raising kids. The general idea is that since men didn’t know exactly when women were ready to conceive, they hung around in a bid to improve their odds of becoming fathers. And to maintain a male’s interest, human females may have evolved other attractions, such as curvaceous breasts. Human females, in fact, are the only primate to have permanently swollen breasts — a significant attraction for males evolved to equate swollen breasts with fertility. That ancient biological history may help explain today’s continued fascination with cleavage among both men and women.

Men have also evolved assets designed to attract a mate. Large muscles, for instance, may have once signaled a man’s prowess as a hunter and defender. But strength alone probably wasn’t enough to attract and keep a mate. To be successful, men also had to show that they had the smarts to be creative and dependable providers, clever enough to find food and shelter for their families in an often hostile environment.

Today, physical attributes such as muscles and breasts may have little meaning in modern societies where most people work in offices and limit their foraging to the local grocery store. But they still hold powerful sex appeal, a fact not lost on advertisers who use bikini-clad supermodels and ripple-chested jocks to sell everything from cars to dish detergent. Sex, it seems, has long been a best-seller.

Overall, less than 3% of mammal and bird species practice monogamy, and in many of those species, cheating or alternative arrangements is common. Men in some cultures, for instance, have many wives. In others, many men share a single wife. A bird called the Jacana, or Lily Trotter, has a similar sex contract. A single female will have four or five male partners, each carefully caring for eggs laid by the female.

Still other creatures carry this idea to an extreme. African mole rats and termites, for instance, live in underground colonies with a single queen that produces all of the offspring in the colony.

As a result, almost all of the colony’s inhabitants are brother and sister. Male elephant seals, in contrast, play king, ruling over a harem that includes every female on a long stretch of beach.

These arrangements, however different, have the same goal: increasing the number of offspring carrying the parents’ genes — or, in the case of termites, the common genes of the entire colony. And in each case, the contracting partners work together for the common goal: the survival of a new generation.

There is nothing more romantic than a moonlit night. So goes many a love song. But for animals from bat rays to wriggling, seagoing palolo worms, the moon is more than a romantic backdrop — it’s a key signal that the time has come to mate.

Such sexual signals are the focus of A TIME AND A PLACE, Part 2 of NATURE’s THE NATURE OF SEX. From the changing phases of the moon to subtle chemical surges, the program outlines the many cues that trigger sexual activity. Indeed, without these landmarks, many animals would send their newborns into the world at the wrong place and wrong time, with little chance of survival.

Consider the Pacific grunion, for instance. Each spring, millions of these little fish fling themselves up onto Pacific beaches to deposit their eggs in the wet sand. But they don’t choose just any night for sex. They ride the spring tide, one of the highest tides of the year, when the moon’s pull is the strongest. The choice ensures that there will be enough big waves to get back to the ocean — and that their eggs will be high enough on the beach to be out of reach of scavenging fish. Arrive a few days early or late, and both fish and eggs will perish. The moon, however, isn’t the only sexual timepiece. The sun is also an important trigger. Many mammals become amorous during the lengthening days of spring — a sign that warm weather is coming, and with it adequate food supplies for their offspring. But for other animals, rain is the most important romantic event. Darkening skies and heavy drops, particularly in the arid plains of Africa, mean that there will soon be enough grass to feed young gazelle and other browsing animals. Not surprisingly, predators such as jackals time their births to arrive at the same time, using the easily captured baby browsers as food for their own young.

Other signals are produced by the animals themselves. Many insects and mammals, for instance, produce chemicals called pheromones, subtle perfumes used to attract the opposite sex. Others change color, shape, or grow special body parts, such as sharp, curled horns, to signal that they are ready to reproduce. Indeed, few sights are more impressive than a bird in colorful breeding plumage, or a fish that has turned as bright as a neon sign to attract a mate. Now, all they need is a nice, romantic, moonlit night . . .

As THE PRIMAL INSTINCT illustrates, sex lives comes in many varieties. Some animals mate for life, while others may spend just a few frenzied seconds with their partner. In some cases, the dad takes care of the kids, while in others the mom does all the work. And in many households, the newborns are left to fend for themselves, and will never meet their parents.

Whatever the household arrangements, however, the reproductive strategy that biologists have dubbed “sex” — in which two individuals combine their genes in an offspring, with each parent typically contributing half of the genetic material — offers advantages. Most of all, sex assures variety. Every newborn produced by sex carries a unique set of genes that may give them a survival advantage in a changing environment. Slightly longer legs could prove the difference between outrunning a predator and becoming just another meal. And a slightly heavier coat of fur, or a thicker layer of fat, may enable an animal to survive a winter that brings a cold end to others. Variety not only brings spice to life, it seems, but is also a key to survival.

Not all organisms need sex to multiply, however. Bacteria, for instance, survive just fine by dividing into two genetically identical copies. Similarly, some creatures — such as the whiptail lizards and aphids featured on THE NATURE OF SEX — can produce genetically identical clones without the benefit of a partner. But these identical offspring can be much more vulnerable to disease and changing conditions than more mixed breeds. That’s why sex, in all its shapes and forms, has proved so successful a reproductive strategy.

Despite its central place in all of our lives, sex remains an often mysterious and poorly understood primal impulse. Researchers are still trying to understand how mates choose each other. Sometimes, the signs of a winner are obvious, such as the sleek coat or colorful plumage that signal good health. But other attractions are more subtle. Only female fiddler crabs, for instance, may ever know if it’s the size of a male’s waving, outsized claw — or something else — that proves so seductive.