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All living humans originated from populations of ancestors who migrated out of Africa less than 100,000 years ago. Learn how scientists have used genetic markers to trace the migration routes and origins of modern human populations.

Inthis lesson students will enter the world of the genome, learning about humanhistory and evolution by examining information about human, Neanderthal, andchimpanzee DNA. Using web interactives and videosfrom The Human Spark, studentswill be introduced to the ambitious Human Genome Project, learn about thegenetic similarities and differences between human beings and our hominidancestors, explore how specific genes manifest themselves in differentorganisms, and discover how genetic information can help us trace a path ofhuman migration all the way back to our earliest ancestors.

DNA from a man who lived in Ethiopia about 4,500 years ago is prompting scientists to rethink the history of human migration in Africa. Until now, the conventional wisdom had been that the first groups of modern humans left Africa roughly 70,000 years ago, stopping in the Middle East en route to Europe, Asia and beyond. Then about 3,000 years ago, a group of farmers from the Middle East and present-day Turkey came back to the Horn of Africa (probably bringing crops like wheat, barley and lentils with them).

This lesson, using segments from the PBS series Faces of America, explores the various types of genetic information contained in the human genome. The Introductory Activity examines the structure and composition of chromosomes and DNA, and can be used as a review or introduction to the topic. Following that, students will participate in a hands-on activity reviewing basic Mendelian genetics and the difference between genotype and phenotype. Students will also learn about different ways of tracing ancestry through DNA, and apply that to patterns of human migration and genetic population sets known as haplogroups. In the Culminating Activity, students will develop methods for determining the genetic heritage of their class, school, or community.

The fates of ice age human groups in Europe were closely linked to climate change, according to an unprecedented study of the genomes of 51 individuals who lived between 45,000 years ago (when modern humans arrived in Europe) and 7,000 years ago. "We see multiple, huge movements of people displacing previous ones," David Reich of the Harvard Medical School said. "During this first four-fifths of modern human history in Europe, history is just as complicated as it is during the last fifth that we know so much more about." 

2:18 Human embryonic development depends on stem cells. During the course of development, cells divide, migrate, and specialize. Early in development, a group of cells called the inner cell mass (ICM) forms. These cells are able to produce all the tissues of the body. Later in development, during gastrulation, the three germ layers form, and most cells become more restricted in the types of cells that they can produce.

The study by researchers from the Wellcome Trust Sanger Institute and collaborators at La Trobe University in Melbourne and several other Australian institutes, challenges a previous theory that suggested an influx of people from India into Australia around 4-5 thousand years ago. This new DNA sequencing study focused on the Y chromosome, which is transmitted only from father to son, and found no support for such a prehistoric migration. The results instead show a long and independent genetic history in Australia.

Human populations have adapted to varying intensities of sunlight with varying tones of skin coloration. The balanced interplay between melanin content and UV absorption allowed populations to successfully migrate from sub-Saharan Africa by influencing levels of two key vitamins: vitamin D and folic acid. This case study explores the evolutionary advantage of different skin tones for the human race; it also emphasizes the absence of scientific evidence for the correlation of abilities, talents, and other complex traits to skin color, and exposes certain social misconceptions linking skin color to specific traits. Although the discussion of race is not always a comfortable fit for science and biology courses, this case study uses the topic as an inherently interesting and important subject for applying basic biological concepts of DNA, the central dogma, and mutations to real world questions of physical difference and skin color. This case has been used in biology courses for non-science majors but would also be appropriate for advanced high school students.

Researchers analysed the genomes of 51 individuals who lived between 45,000 years ago and 7,000 years ago. The results reveal details about the biology of these early inhabitants, such as skin and eye colour, and how different populations were related. It also shows that Neanderthal ancestry in Europeans has been shrinking over time, perhaps due to natural selection. The study in Nature journal shines a torchlight over some 40,000 years of prehistory, showing that ancient patterns of migration were just as complex as those in more recent times.