Some weeks back I was in the beautiful city of my childhood, Brooklyn, USA. (For those of you not in the know Brooklyn was it's own city until “the mistake of '98” that is, 1898, when we reluctantly joined with “New York City;” most of us have been lamenting it ever since.) I was visiting my beloved undergraduate alma mater, Brooklyn College, to meet with my friend and the learned Guest Editor of this Special Issue, Professor Alfred Rosenberger. The college's Georgian architecture is beautiful this time of year and has been used as the setting for many movies. Indeed, I was recently watching Spinning into Butter (Gilman and Atchinson,2007), a story set in a college in bucolic Vermont, with two of my tax deductions, when one of them noted, “Gee, that's a beautiful campus.” “That's 'cause it's Vermont and everything is green and pretty there,” added my Ivy League know-it-all. “Actually,” I interrupted, that's Brooklyn College. “Sure, Dad,” they laughed in unison, “and the Dodgers are moving back too!” “Want to bet?” I gamely responded. “If I'm right, you clean the garage; if you're right, new iPhones!” They eagerly took up the gauntlet and laughed…until the credits rolled with acknowledgements to—you guessed it—Brooklyn College! I really like my clean garage.
Upon arrival, I meandered down the verdant pathways to Ingersoll Hall, the main science building. This is where I spent most of my undergrad days, as did scores of other science neophytes, many of whom, like Stanley Cohen (BC'41, 1986 Nobel Laureate in Physiology or Medicine) went on to distinguished careers in varied areas of Medicine, Biology, Chemistry, and Physics. Returning to BC is always poignant for me, for it was here that I cemented both my love for science and began to focus seriously on studying my boyhood fascination with monkeys (see Laitman,2010).
Today's excursion led me to the laboratory of the above-mentioned Alfie Rosenberger, one of the brightest and most hard working (and often quite controversial) figures in the world of monkeydom. He's one of the really sharp folks, those that know not only the lumps and bumps of our close brethren, but what they may mean, and how if you tie them all together and look really close you can figure out relationships going back millions of years. His particular love, and the lens through which he views and interprets evolutionary events, are the monkeys of the New World. To put this group in a larger perspective for those who do not spend their hours riveted to our hairy relatives, we are primates, spelled with a capital “P” and pronounced “pri-MAY-tees” only when used as the proper noun, such as in the Order Primates. Primates can be further subdivided many ways (anthropologists must make a living!) but a basic breakdown is to separate us into two “Suborders”: Strepsirhini (lemurs, lorises, and their ilk) and Haplorhini (monkeys, apes, and us; many include the tarsiers with this group, but I don't want to get into those arguments here—anthropologists can bite more then the tarsiers!) The Haplorhini are usually subdivided further into two Infraorders, the Catarrhini—Old World monkeys, apes and us (here “Old World” denotes living species from Africa and Asia and macaques from the rocks at Gibraltar, not the villages of eastern Europe as my relatives would think; ancestors of some were in Europe, however); and the Platyrrhini, the New World monkeys (living and extinct monkeys from the Americas; some 16 living genera and greater than two dozen extinct ones.) (By the way, if you are curious as to all the “…rhini” suffixes, it's due to a focus on nose shapes—Ptatyrrhini means flat nosed—which was the feature centered upon when this classification was suggested by Reginald Pocock in a series of papers back in the early part of the 20th century; see Reviews in Hershkovitz,1977; Szalay and Delson,1979).
In the world of primates, the New World monkeys are clearly the “Rodney Dangerfields” of our relatives, rarely getting their due respect. Focus has usually been on our evolutionarily closest relatives, the gorillas, chimpanzees and orangutans—the “Great” apes (pretty pompous name, if you think about it; the “Lesser” apes, the gibbons and siamangs, have been complaining for years)—or certain groups of Old World monkeys such as baboons or macaques. Those groups get all the television specials and cool people going to live with them; neither Jane Goodall nor Diane Fossey ever cuddled up to New World monkeys.
Disrespected as they may be by the general public or primate observer megastars, New World monkeys are adored by the primate cognoscenti as they encompass an incredible, and relatively untapped, world of variation in form, functional anatomy and evolutionary adaptation. How they arrived in the New World has been a source of much discussion and debate, yet they probably came from Africa some 30 million years before the present (look at a map and see how South America fits snugly into the African continent; historically the land masses were much, much closer and separated over time.) New World monkeys are fascinating, showing features often not found in the better known baboons or apes such as prehensile tails or extraordinary throat pouches (or even pneumatized hyoid bones) used in sound amplification. Even the number, and often shape, of their teeth differ from their relatives across the Pond. New World monkeys range from the miniscule marmosets and tamarins (the pygmy marmoset is the world's smallest monkey weighing in at some 100 g)—many of who pair bond for life and exhibit extraordinary parental care—to the large woolly spider monkeys (10,000 g). Unlike many of their Old World brethren, New World monkeys are almost exclusively arboreal, and have evolved a stunning array of anatomical modifications to maximize the many micro-niches of the trees they inhabit. And what they eat and how they eat has been a smorgasbord of fascination for dental anthropologists and primate behaviorists for decades (For reviews see: Martin,1990; Kinzey,1997; Fleagle,1999; Rosenberger and Hartwig,2001).
Uncovering the anatomical wonders of this part of the family—and putting the fascinating array of tails, teeth, assorted bones, and skin coverings into an evolutionary framework—is the focus of this special Issue on “Evolutionary and Functional Morphology of New World Monkeys” (Rosenberger,2011). Rosenberger has assembled a troop of sharp-eyed (and sharp-scalpeled) anatomists who here present cutting-edge interpretations on a range of topics that will rivet even those unfortunate enough not to spend their days studying members of our clan. I defy anyone, including seasoned primatologists, to read this special issue and not come away with exclamations of “gee I didn't know that?” or “primates have those?”
The topic of a number of articles focuses upon the locomotor abilities and presumed adaptations found in both living platyrrhines and reconstructed for extinct relatives. Fascinating novel hypotheses are offered suggesting that some ancestral monkeys may have locomoted via suspensory, and somewhat terrestrial behaviors, similar to living chimpanzees. Others dissect with intensity new ideas on those incredible prehensile tails and what literally underlies their grasping abilities, from the nature of the skin to mechanoreceptors. Hypotheses are offered that not all prehensile tails are the same, and subtle, yet significant differences abound. Still others dissect the fineries of how locomotor substrates (branches and trees to you and me) may have evolutionarily influenced—“preadapted”—species to their current functional modes of movement. And while were still on the postcranial world, how about a fascinating paper on how nails and claws came to be (did you know some of our primate relatives—beside some of my in-laws—have claws?)
Cranial specializations are encompassed with equal energy, with studies assessing numerous parameters of the biomechanics involved in skull and tooth shape in relation to feeding mechanisms and food selection (they might not have McDonalds, but our New World relatives munch on an array of leaves, fruits and seeds that they have been uniquely designed to maximize.) Cutting-edge technologies—such as three-dimensional geometric morphometrics of laser scanned molars—are used in a number of the studies to bring new and, often, provocative insights into how these monkeys function. And beyond the teeth and bones, studies are represented that delve into brain size and what this may mean for cognitive abilities; and the always fascinating vomeronasal organ and how it develops ontogenetically and evolutionarily in New World species.
Finally, but a key thread that flows through all the studies, is the placement, and understanding of the features explored within the lens of evolution. How, why, and often when, traits being described came to be—what forces shaped them, what preadaptations may have existed—frames much of the dialogue in this Special Issue. The scientists whose works are represented herein are both outstanding comparative anatomists and evolutionary thinkers and place much of their discussions within this context. Given this predilection, they are always searching, seeking, to understand the big question: how do the primates they are studying fit into the greater picture? They are, in essence, seeking the “Holy Grail” for evolutionary biologists: What does the evolutionary “tree” of our kind look like?
Many years ago—back in 1943—there was not much to cheer about back in Brooklyn. World War II still raged on, and the Dodgers lamely finished the season without winning the pennant (the New York Yankees won the World Series, of course.) One thing that did warm the hearts of Brooklynites—and later much of the world—was a wonderful, best selling, work of fiction by Betty Smith (1943), A Tree Grows in Brooklyn. Through the warm and meaningful pages, the history of a family was dissected, and the evolution of where they came from, how they came to be, and how they related to each other, was viewed in exquisite and loving detail. The “tree,” of course, was the metaphor for life's relationships and continuum.
It's good to know that a “tree” is still lovingly growing in Brooklyn, albeit this time charting the path and relationships of other fascinating relatives, those wondrous monkeys of New World.