By Gerald F. ColvinLike many others of a certain age, ?I now have more time to observe the wildlife in my backyard. Just recently I watched a concerned bluebird mom stuff yet one more day-old mayfly into her son’s already-overflowing beak. Worried for their safety, I quietly maneuvered them away from the middle of the utility road bordering my property. The youngster flew to a crash landing some 10 feet onto the grass, while his mother settled several feet farther away on the neighbor’s wrought-iron fence. After time out to study all things new, the son finally landed, all feathers and flutter, on the fence beside his mother.
 
Almost all the juvenile’s insouciant tracking of mom was dictated by imprinting, a phenomenon occurring when a young animal comes to recognize another animal, person, or thing as its parent. I had taught both imprinting and Mendelian genetics in high school biology, and later introduced hundreds of developmental psychology college students to photos of ethologist Konrad Lorenz leading his troop of waddling goslings down a garden path toward his pond, where he would spend long hours up to his neck in the water with them. Although imprinting is natural, in most instances its occurrence depends on a precise window of time and opportunity.
 
Classic Genetics and Epigenetics
In classic genetics we learned that fetuses inherit two copies of a gene, one from each parent, with both actively shaping how the child develops. In epigenetic imprinting, however, one of those copies is turned off by molecular instructions coming from either of the parents.
 
Epigenetics refers to changes in phenotype (appearance) or gene expression caused by mechanisms other than changes in the underlying DNA sequence, hence the name epi (Greek “over/above”) genetics. These changes may remain through cell divisions for the remainder of the cell’s life and may even last for multiple generations. But there is no change in the underlying DNA sequence of the organism; instead, nongenetic factors cause the organism’s genes to behave (or “express themselves”) differently.
 
This process of “imprinting” information on a gene is thought to occur during the normal reproductive union, and means that a child will inherit only one working copy of that gene. Thus, if the only functioning copy is damaged or lost, there’s nothing left to bridge ?the gap.
 
Researchers have now found that many of the newly identified imprinted genes lie within genomic regions associated with the development of such major diseases as cancer, diabetes, autism, and obesity. Duke geneticist Randy Jirtle worries that because human imprinting is largely epigenetic, it can change a gene’s function without even altering the sequence of its DNA! Imprinted genes are unusually susceptible to pressures from our environment—even by what we eat, drink, and breathe. And epigenetic changes can be inherited! “I don’t think people realize that,” laments Jirtle.¹
 
Scientists estimate that imprinted genes comprise approximately 1 percent of the human genome, and until recently only several dozen had been identified. Using a new decoding process, however, investigators have found 156 new likely imprinted genes. Still, because gene expression varies from tissue to tissue with most genes switching on and off over time, it will be difficult to demonstrate that all 156 new genes are truly imprinted and not just statistically likely candidates.²
 
Songbirds—Imprinting and Practice Make Perfect
Recently I watched an adolescent mockingbird approach his mom and begin stamping his feet up and down as if jogging in place. His frenetic display must have meant, “Hey, Mom! Feed me! I’m starving!” because that’s exactly what she did. Still, mockingbirds have to be among the most intelligent of all North American birds.
 
But because they are so intelligent they are also more inquisitive, and so are often considered annoying busybodies. Each year during nest-building, brood-feeding, and “I’m-learning-to-fly” times, mature and juvenile mockers flit from stake to stake in my newly tilled garden while contesting my ownership. I’m guessing their sense of territory is inborn, because every generation feels the same way about my noisy agricultural activities so near their ancestral hedgerow!
 
Learning to Sing
Though their desire to mimic may be instinctive, the mockingbird’s ability to learn through practice establishes it as an oscine Meistersinger. Only birds and some mammals, such as whales, humans, and a few bats, possess the ability to learn songs.
 
The vocalizations of such birds as chickens, doves, and flycatchers are prewired. When raised in acoustical isolation or are deafened before they hear their fellow birds sing, they nevertheless sing normal songs as adults.
 
In contrast, songbirds actually listen to the songs of other individual birds and practice them in a series of well-documented stages of song development. The stages can be grouped into two phases: (1) the sensory acquisition phase in which hearing a song is paramount, and (2) the sensorimotor phase in which practice is paramount.³
 
What We Can Learn
The early development of birdsong provides one of the best working models of how a complex, learned motor skill develops—in birds or humans! Neurobiologists can now track how specific parts of the brain’s song systems participate in the process of song development. Some virtuoso birds (such as my “Tennessee mockers”) continue adding new vocalizations to their repertoires as long as they live. These “open-ended” learners hone to near perfection other species’ songs!
 
Isolation from the model songs of adults of the species during the critical learning period will permanently impede a young songbird’s singing skill, and it will never develop a truly normal song for its kind. Although individual birds isolated at an early age still sing, their songs will be less complex, boast fewer notes per syllable, and display less frequency modulation than do normal songs.
 
Imprinting occurs when a young animal comes to recognize another animal, person, or thing as his or her parent. Human epigenetic imprinting reveals that a gene’s function can change without altering the sequence of its DNA. Such imprinted or altered genes are unusually susceptible to what we eat, drink, and breathe. Unfortunately, epigenetic changes can be inherited!
 
As a parent and grandparent, let me highlight a number of worthy points in review: (1) the importance of listening, (2) the value of practice, (3) the need for early exposure to great themes, (4) the recognition of our need for partnership with the Divine, and (5) an acknowledgment that God delights in occasionally surprising us with unschooled prodigies. But an even more crucial point is our need as parents to “seek after righteousness” that we might reinforce our children and grandchildren against the challenges awaiting them.
 
We have also been called to strengthen our moral resolve, and now we see that our intemperance can epigenetically impact our children’s physical, mental, and spiritual powers. We already know that drug users transmit their insatiable craving, inflamed blood, and irritable nerves to their newborns. “The licentious often bequeath their unholy desires, and even loathsome diseases, as a legacy to their offspring. . . . To a great degree parents are responsible not only for the violent passions and perverted appetites of their children but for the infirmities of the thousands born deaf, blind, diseased, or idiotic.”⁴
 
Geese Are Smart—?But Not That Smart
On a crisp Minnesota fall afternoon a 4-year-old was helping his mother rake leaves in the front yard of their farmhouse. Glancing up just in time to see a flock of geese flying over, Mom pointed out that the geese were flying in a formation shaped like a v. The preschooler watched them patiently as they disappeared over the horizon, and then he turned to his mom and asked, “Do they know any other letters?”
 
It’s easy to smile at the youngster’s query, but he unknowingly introduces an even more basic concern: How much of our knowledge depends on our genetic prewiring, and how much on observation and practice? One thing is for certain among us humans: God has equipped us with fantastic capacities that most of us are only recently realizing!
 
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1 “Human Genome Has Four Times More Imprinted Genes Than Previously Identified,” ScienceDaily, online at www.sciencedaily.com/releases/2007/11/ 07113007?5016.htm, accessed May 19, 2009.
2 Ibid.
3 Frank B. Gill, Ornithology, 3rd ed. (New York: MacMillan, 2007), p. 230.
4 Ellen G. White, Patriarchs and Prophets (Mountain View, Calif.: Pacific Press Pub. Assn., 2005), p. 561.
 
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Gerald F. Colvin, Ph.D., Ed.D., recently retired as a professor of Education and Psychology from Southern Adventist University in Collegedale, Tennessee. This article was published December 8, 2011.