Table 1.

Chronological table of diffusion experiments. (This table is directly derived from table S1 in the electronic supplementary material, which offers a comprehensive survey of methods and conclusions, together with Latin names of species studied, and further evaluative comments. Des. str.=design strength, following the scheme described in table 2 and explained fully in the text, where higher numbers represent designs judged more powerful in identifying diffusion based upon social learning: those of levels 3 and above incorporate control conditions that discriminate social from non-social learning, and are represented in italics. The column ‘cultural diffusion’ summarizes evidence for diffusion of the behaviour pattern of interest, where des. str.=3 or more. Numbers of transmissions within chains are shown in parentheses; ?=number of transmissions unknown. For detailed information see table S1 in the electronic supplementary material.)

study content	species studied	publication	des. str.	cultural diffusion? (no. of transmissions)
Successive replacements in trios exposed to alarming objects	chimpanzees	Menzel et al. (1972)	3 B	habituation effect stable (17)
Transmission chains, seeded with alarm calls to arbitrary object	blackbirds	Curio et al. (1978a,b)	3 C	alarm calling stable (6)
Whole groups exposed to novel cues to buried food; spread of discovery in groups documented	baboons, vervets	Cambefort (1981)	1 A	?
Three nut-cracking chimpanzees mixed with nine naive ones	chimpanzees	Sumita et al. (1985)	2A	?
Models pecked through paper covers, in wild and captive flocks	pigeons	Lefebvre (1986)	4 A	piercing stable over 55 days
Spread of spontaneously initiated nut-cracking recorded in group	chimpanzees	Hannah & McGrew (1987)	2 A	?
Transmission chains seeded with models digging up carrot pieces	rats	Laland & Plotkin (1990)	4 C	digging stable (8)
Replication of 1990 study but incorporating a 24 hour delay	rats	Laland & Plotkin (1992)	4 C	stability less, with delay
Opportunity provided for group to use tools to probe for honey	chimpanzees	Paquette (1992)	1 A	?
Rearing conciliatory stump-tailed macaques with rhesus, among whom reconciliation is relatively rare	rhesus macaques	de Waal & Johanowicz (1993)	5 A	effect stable over six-week post-model phase
Transmission chains seeded with rats preferring different flavours	rats	Laland & Plotkin (1993)	7 C	transmission shown (8) but fidelity variable
Nuts cracked elsewhere introduced; spread in group recorded over several years	chimpanzees	Matsuzawa (1994) and Biro et al. (2003)	1 A	?
Successive replacements in groups with initial flavour preferences	rats	Galef & Allen (1995)	5 B	transmission shown, with slight waning (over 14)
Wild groups seeded with individuals trained to open specific small doors to feed	magpie jays (wild)	Langan (1996)	7 A	door opening stable over 3 days, but not door chosen
Spread of dipping for honey with specific natural tool documented	chimpanzees	Tonooka et al. (1997)	1 A	?
Founder shoals were seeded with preference for one of two routes	guppies	Laland & Williams (1997)	5 B	differences transmitted (7) but waned by half
Similar to 1997 paper but more efficient alternative available	guppies	Laland & Williams (1998)	5 B	differences transmitted (7) but waned
Groups with mixed naive and experienced fishes created	guppies	Reader & Laland (2000)	2 A	?
Young cowbirds housed with adults singing either of two different songs; repeated once first cohort became adults (models)	cowbirds	Freeberg (1998) and Freeberg et al. (2001)	5 A	?
Spread of route preference: models in familiarity and experience	guppies	Swaney et al. (2001)	2 A	?
Spread logged off using either of two routes to escape a threat	guppies	Brown & Laland (2002)	7 A	social transmission not found
Flocks exposed to models feeding on blood from mock hen	chickens	Cloutier et al. (2002)	4 A	rapid waning over three transitions
Wild, banded birds exposed to model using novel foraging method	keas (wild)	Gajdon et al. (2004)	3 A	no significant evidence of social transmission
Captive chimpanzees given rough leaves used medicinally in wild	chimpanzees	Huffman & Hirata (2004)	1 A	?
Juveniles exposed to adults using either of two methods to get juice	brown capuchins	Fragaszy et al. (2004)	6 A	techniques spread but social learning unclear
Two groups each seeded with model using tool in different way	chimpanzees	Whiten et al. (2005)	7 A	moderate fidelity but stable over two months
Two transmission chains; opening artificial ‘fruit’ using alternative methods, plus control condition lacking model	chimpanzees children	Horner et al. (2006)	7 C	stable (8)
Two groups, each seeded with arbitrary convention to obtain food	chimpanzees	Bonnie et al. (2006)	7 A	spread to half group: stable, one corruption
As for 2005, but transfer between groups in foraging techniques	chimpanzees	Whiten et al. (2007)	6 A	stable, spread across three groups
Replication of Whiten et al. (2005), with one untrained model	chimpanzees	Hopper et al. (2007)	7 A	minimal evidence of social transmission
Two groups each seeded with a different foraging technique (via video) of related species model	colobus monkeys	Price & Caldwell (2007)	6 A	stable after 5 days with no model, one corruption
Replication of Horner et al. (2006) with appropriately modified task	brown capuchins	Dindo et al. (2008)	7 C	stable (4)
Successive replacements of fishes focused on novel food task	guppies, playfish	Stanley et al. (2008)	4 B	stable (13)