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Two Approaches to Biology: Holism vs. Reductionism

Explore the concepts of holism and reductionism in biology, understanding complex systems by studying simple ones and vice versa. Discover emergent properties in organisms and groups in relation to individual components. Delve into nervous system functions in perceiving and responding to the environment, examining examples like slime mold aggregation and ant colony organization. Learn how society is influenced by emergent properties and the implications of manipulating complex systems. Prepare for a guest speaker session and homework on the topic.

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Two Approaches to Biology: Holism vs. Reductionism

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  1. Two ways to think about the world: atoms molecules organelles cells tissues organs systems organisms environment Reductionism

  2. Two ways to think about the world: atoms molecules organelles cells tissues organs systems organisms environment Reductionism holism

  3. Two Approaches to Biology holism reductionism

  4. To understand complex systems, we must understand simple systems and visa/versa holism reductionism

  5. an, components, emergent, group, individual, none, of, or, organism, possess, properties, that, the

  6. an, components, emergent, group, individual, none, of, or, organism, possess, properties, that, the Emergent properties- properties of an organism or group that none of the individual components possess. From: “Emergence” by Steven Johnson (2001)

  7. Emergent properties- properties of an organism or group that none of the individual components possess. From: “Emergence” by Steven Johnson (2001)

  8. Nerves allow us to perceive the environment while the brain integrates the incoming signals to determine an appropriate response. from “Biology”Campbell Response

  9. from “Biology”Campbell Nervous systems can make complex calculations with cells that are on/off (1 or 0)

  10. There is no boss in the brain. Nor directions in how to make one. from “Biology”Campbell

  11. Plant can integrate information and make decisions without a central nervous system. http://www.ted.com/talks/lang/eng/stefano_mancuso_the_roots_of_plant_intelligence.html

  12. Slime mold aggregation from “Biology”Campbell

  13. Slime mold aggregation from “Biology”Campbell

  14. It has been known for some time that slime mold aggregation occurs via cAMP signaling

  15. It was assumed that certain cells (pacemakers) signaled the others to aggregate

  16. But, no one could find the pacemakers single cell

  17. Each cell releases cAMP and responds to local conditions. Cells follow cAMP trail to aggregate with other cells. cAMP cAMP cAMP cAMP single cells cAMP cAMP cAMP cAMP cAMP cAMP cAMP

  18. Each cell releases cAMP and responds to local conditions. Cells follow cAMP trail to aggregate with other cells… self-organizing cAMP cAMP cAMP cAMP single cells cAMP cAMP cAMP cAMP cAMP cAMP cAMP

  19. Ant colonies: this is our concept of how an ant colony is organized.

  20. The Queen is fed and lays eggs, but gives no orders. http://www.antstop.co.uk/nests/nest-static.jpg

  21. So who is in charge?

  22. Harvester ant wokers have four distinct tasks that they can perform: foraging, patrolling, nest maintenance, and midden work

  23. Each ant uses local information to determine what to do. Can do this without central command. With a few simple criteria, the plan comes together.

  24. Interaction rate informs harvester ant task decisions Fig 2. Interaction rate informs harvester ant task decisions. M. Greene D. Gordon. Behavioral Ecology 18: 451-455

  25. Patroller return rate increases about 30 min. before foragers leave nest time of day (am) Fig 2. Interaction rate informs harvester ant task decisions. M. Greene D. Gordon. Behavioral Ecology 18: 451-455

  26. Adding beads (coated in patroller extract) at the correct rate can induce forager activity Fig 1. Interaction rate informs harvester ant task decisions. M. Greene D. Gordon. Behavioral Ecology 18: 451-455

  27. Each ant uses local information to determine what to do. Can do this without central command. With a few simple criteria, the plan comes together.

  28. Much of our society is based on emergent properties.

  29. Much of our society is based on emergent properties. Problems can arise as individuals try to manipulate the system.

  30. Much of our society is based on emergent properties. Problems can arise as individuals try to manipulate the system. Google Bombs:“Miserable failure” directed searchers to the White House biography of G.W. Bush. http://news.bbc.co.uk/2/hi/americas/3298443.stm

  31. Not everyone uses the same criteria to make decisions...

  32. …Stock Market prices set by what other people think will happen.

  33. Much of our society is based on emergent properties: Democracy- as a group can we make better decisions than an individual?

  34. Next: Guest Speaker and homework #9

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