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Related Concept Videos

Migration00:53

Migration

Migration is long-range, seasonal movement from one region or habitat to another. This common strategy, carried out by many different organisms around the world, is an adaptive response that typically corresponds to changes in an organism’s environment, like resource availability or climate. Migrations can involve huge groups of thousands of animals as well as single individuals traveling alone and can range from thousands of kilometers to just a few hundred meters.
Crossing over01:34

Crossing over

Unlike mitosis, meiosis aims for genetic diversity in its creation of haploid gametes. Dividing germ cells first begin this process in prophase I, where each chromosome—replicated in S phase—is now composed of two sister chromatids (identical copies) joined centrally.
The homologous pairs of sister chromosomes—one from the maternal and one from the paternal genome—then begin to align alongside each other lengthwise, matching corresponding DNA positions in a process called synapsis.
In order to...
Crossing Over01:30

Crossing Over

Crossing over is the exchange of genetic information between homologous chromosomes during prophase I of meiosis I. Genetic recombination gives rise to allelic diversity in the newly formed daughter cells. In humans, crossing over produces genetically distinct haploid egg and sperm cells that undergo fertilization to produce unique offspring. Before cell division starts, the germ cell’s chromosome(s) undergo duplication in the S phase of the cell cycle. As the cells enter prophase I, duplicated...
Crossing Over01:34

Crossing Over

Unlike mitosis, meiosis aims for genetic diversity in its creation of haploid gametes. Dividing germ cells first begin this process in prophase I, where each chromosome—replicated in S phase—is now composed of two sister chromatids (identical copies) joined centrally.
The homologous pairs of sister chromosomes—one from the maternal and one from the paternal genome—then begin to align alongside each other lengthwise, matching corresponding DNA positions in a process called synapsis.
In order to...
Design Example: Alignment of a Road Line Using GIS01:17

Design Example: Alignment of a Road Line Using GIS

The alignment of a road line using Geographic Information Systems (GIS) is a critical process in civil engineering, combining advanced technology with practical decision-making. This methodology begins with the collection of geospatial data, including information on land cover, geomorphology, drainage patterns, slope, and contour details. Such data is typically acquired through satellite imagery and GIS tools, offering a comprehensive understanding of the terrain.Once the data is gathered, it...
Gene Flow02:39

Gene Flow

Gene flow is the transfer of genes among populations, resulting from either the dispersal of gametes or from the migration of individuals.

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Related Experiment Video

Updated: Jun 24, 2026

Assessing Human Spatial Navigation in a Virtual Space and its Sensitivity to Exercise
06:17

Assessing Human Spatial Navigation in a Virtual Space and its Sensitivity to Exercise

Published on: January 26, 2024

Human migrations: the two roads taken.

Dennis H O'Rourke1

  • 1Department of Anthropology, University of Utah, 270 S. 1400 E., Rm. 102, Salt Lake City, UT 84112, USA. orourke@anthro.utah.edu

Current Biology : CB
|March 13, 2009
PubMed
Summary

Early Americans arrived from Asia, with new genetic evidence suggesting two distinct migration waves. These migrations occurred simultaneously but independently from different Asian populations.

Area of Science:

  • Genetics
  • Anthropology
  • Archaeology

Background:

  • The peopling of the Americas from Asia is a key topic in human history.
  • Previous research indicates migration occurred by the end of the last ice age.
  • The precise timing and source populations remain subjects of ongoing investigation.

Discussion:

  • Analysis of rare mitochondrial haplogroups provides new insights into early American migrations.
  • The study suggests two separate migration events into the Americas.
  • These events likely originated from distinct Asian source populations.

Key Insights:

  • Two independent Asian migrations contributed to the early peopling of the Americas.
  • Mitochondrial DNA analysis reveals simultaneous, yet separate, ancestral origins.

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Competitive Homing Assays to Study Gut-tropic T Cell Migration

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Assessing Human Spatial Navigation in a Virtual Space and its Sensitivity to Exercise
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Assessing Human Spatial Navigation in a Virtual Space and its Sensitivity to Exercise

Published on: January 26, 2024

Competitive Homing Assays to Study Gut-tropic T Cell Migration
10:25

Competitive Homing Assays to Study Gut-tropic T Cell Migration

Published on: March 1, 2011

  • This finding clarifies the complex genetic landscape of the first Americans.

    • Outlook:

    • Further genetic and archaeological research can refine our understanding of these migration events.
    • Investigating additional genetic markers may reveal more about the diversity of early American populations.
    • This study opens new avenues for exploring the intricate history of human settlement in the Americas.