Life in the troop has certainly had an incredible impact on little Frank’s social development, but even more impressive is the impact it has had on Frank’s family. Back when Frank was born and we realized we were going to have to intervene at some level, we had many candid discussions about how best to raise this kid, without hampering his true “gorilla skills.”

Although the San Diego Zoo has a significant amount of experience and a tremendous amount of success hand-rearing great apes, we recognized that we could only teach an infant gorilla so much about how to become a successful adult. We weighed the pros and cons of our level of interaction and determined the threshold for how much impact our influence would have compared to that of his family. We knew we could teach Frank some of the tools he would need to keep him healthy, but we knew we would never be able to teach him how to “speak” gorilla. The fact that the females in his family (mom Azizi and aunts Imani and Ndjia) were all inexperienced moms, we hoped that raising Frank as a team would allow them to get practice in the skills that make a mother successful. (Read post, It Takes a Village to Raise a Gorilla.)

As a bunch of self-described “primate nerds,” we looked for some of the more subtle signals that would indicate a mutual learning process. The most obvious was transportation and locomotion. Generally speaking, we look for milestones in physical aptitude, and we start with the most basic: knuckle walking, climbing, and riding on the adult females’ backs. Although the physical adaptations for knuckle walking already exist, it does take some practice to get it right, and most infants begin their first forays into walking with an open hand (or palmer) approach. It takes a few months of practice, but one can see the subtle movements that lead to a more curled under, traditional knuckle walk.

We waited and watched, and Frank grasped this skill right on time. The trick then becomes determining when to open your hands for climbing and gaining enough balance to knuckle your way up onto an uneven surface (logs, rocks, etc.). When you look at some of Franks photos, you can see how his hands are much more parallel with the ground than the adults’ hands are when he climbs. Although he is using his knuckles to make contact, he is still putting most of his weight on his palm and hands. Subtle, but really fascinating if you’re a primate nerd!

Climbing was a little bit easier and came on much more effortlessly than the whole knuckle-walking thing. We made sure he had plenty of climbing opportunities in his bedroom area, and of course grasping is one of the first physical skills that develop in infant primates. As soon as a baby primate is born, he or she needs to be able to grasp on to Mom even while sleeping. The transition from using this skill on Mom to using it on a rope or a tree is generally a smooth one. This was certainly the case with Frank, and we often marveled over how someone that was so ungainly on all fours could happily suspend himself by one hand. This has now evolved into some pretty tricky moves in which he can suspend himself by his right hand while beating his chest with the left. Then comes the need to coordinate the feet in the whole climbing process, sometimes keeping a firm grasp on one object with his foot while negotiating a gap with his upper body. This still results in a sloppy tumble about half the time, but he maintains the confidence to keep trying, which is another trait that is reinforced by his close relationship with his family.

Being transported dorsally (on the back) or ventrally (on the chest) by one of the females is also something that takes a team effort. The females do most of the work to get him into position, but he needs to recognize the signals and cooperate a bit when the position gets awkward. Most female primates develop their own style when it comes to transporting a baby, and these three girls are no different. Azizi is the master of the ventral hold and is not real keen on the dorsal hook up. Ndjia is pretty good with both, but often prefers what we call the “furry football” approach in which she carries him by the rump with his arms and legs wrapped around her forearm. It’s a bumpy ride and Ndjia’s limp (from a leg injury as a juvenile) makes it look pretty uncoordinated. It suits her personality, however, and it sets her up nicely for a perfect tumble in which she ends up laying on her back with Frank in perfect tickle position.

Imani is by far the best at all of these moves and also seems to be very in tune with when he needs help as opposed to when he simply wants help. She often waits for him to negotiate difficult terrain on his own and withholds her assistance until it is truly necessary. This is an excellent example of how that relationship is one that must be learned through trail and error. It builds confidence in both parties and helps Frank develop physical skills to compliment his explorative nature. When you get that chance to watch Frank and Imani interact, you will notice how she meters her attention and allows him to struggle a bit before lending a helping hand. This is allowing her to practice some very valuable maternal skills and teaches her when to intervene and when whining is a necessary step in learning.

As of late, we have also seen an incredible but subtle change in the entire troop dynamics with respect to the relationships each has with one another. Generally speaking, female gorillas form the strongest adulthood bonds with the silverback as opposed to the other females in the troop. This is an essential feature to gorilla social structure, and it reinforces the millions of years of social evolution that results in a single male group. Of course, the relationship between mother and offspring is also an incredibly important one, but proximity and contact make that one much more obvious. Frank’s family is a relatively young troop, and although Paul Donn (the silverback and Frank’s dad) was showing signs of a competent troop leader, we knew that the introduction of an infant would solidify the bonds of the family.

Before Frank was born, it was not uncommon for the three females to spend most of the day in proximity to one another while Paul rested in his favorite nap spot on the other side of the exhibit. About two months ago we started to see a subtle migration of the females to the periphery of Paul’s nap spot. Now, more and more frequently we can see the troop within visual contact of one another and the females spending less time out of range from their silverback. Paul and Frank have an incredible bond, and when they are inside it is usually the two of them who spend the most time together, which in turn draws the females in closer due to Frank.

Once again, the little guy’s impact on the entire troop has been almost immeasurable and has been the key to our goal of allowing these magnificent animals to express natural, normal gorilla behavior so that we can share that special connection with our guests. Please join us for the San Diego Zoo’s Discovery Days: Absolutely Apes, presented by Bridgeport Education, September 17 to 20, and learn more about all of our amazing great apes. Frank is serving as the San Diego Zoo’s ambassador for the WAZA (World Association of Zoos and Aquariums) 2009 Year of the Gorilla celebration.

Greg Vicino is an animal care supervisor at the San Diego Zoo.

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