Dry Holocene Events and Human Dry Holocene Events and Human Occupation in South America – Occupation in South America – An Archaeological Point of ViewAn Archaeological Point of View

Araujo, A.G.M.Neves, W.A.

Piló, L. B.

Laboratório de Estudos Evolutivos Humanos – LEEHInstituto de Biociências - USP

Lagoa Santa and the Lagoa Santa and the “Archaic Gap”“Archaic Gap”Area subject to research since 1830´s

(Peter Lund).Hundreds of human skeletons found.Dated human remains cluster around

two intervals: 10,000 – 8,000 and 2,500 – 1,000 C14 yrs. BP.

Archaic Period is absent in the area.

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Figure 3. A rchaeo logica l s ites (num bers) and paleoenvironm enta l studies (le tters) c ited in the text.1= Lagoa S anta; 2= Santana do R iacho ; 3= Lapa do Boquete ; 4= Lapa do D ragão ; 5= Lapa P equena6= G ruta do G en tio II; 7= Lapa do Vara l; 8= G O -JA -01; 9= M T-G U -01; 10= B A-R C-28; 11= Ab rigo do P ilão12= F urna do Estrago ; 13= Pedra Furada (S ão R aim undo Nona to area); 14= P edra P intada ; 15= P eña R oja16= A tacam a; 17= Inca Cueva 4 ; 18= C ueva Tix i, Cerro E l S om brero, C erro La Ch ina ; 19= Agua de La Cueva

A = Lagoa dos O lhos, Lagoa Santa; B= Lago S ilvana and Dom Helvéc io ; C= Lago do P ires and Água P re ta de Ba ixo; D = Sa litre ; E = S erra Negra; F= C rom ínia ; G = Águas E m endadas, Lagoa Bonita , and Lagoa Feia; H= Ica tu Dunes; I= Toca da B oa V ista ; J= Cara jás; K = H um aitá ; L= R io Negro D unes; M = Lake P a ta ; N= Pantano de M onica ; O = Fazenda do P in to ; P = S e rra R io do R astro ; Q = M orro da Ig re ja ; R= S e rra B oa Vista ; S = Vo lta Velha ; T= S erra C am pos G era is ; U = P araná R iver; V = R io C la ro; W =B otucatu ; X = Anhem bi; Y= Jagua riúna.

Dated human skeletons from Dated human skeletons from Lagoa Santa and environsLagoa Santa and environs

Lagoa Santa Human Skeletons

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Searching for Other Evidences of Searching for Other Evidences of Human Abandonment During the Human Abandonment During the HoloceneHoloceneIs the “Archaic Gap” a generalized

phenomenon?Sources of archaeological

information: the Lagoa Santa Project and published data.

Rockshelters x open-air sites.

Rockshelters in Central BrazilRockshelters in Central Brazil

Most of them show gaps in the human occupation.

These gaps usually take place in the mid-Holocene.

The gaps do not always fall in the same chronological interval.

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Lagoa Santa (MG)Santana Riacho (MG)

Boquete (MG)Lapa Dragão (MG)

Lapa Pequena (MG)Gruta Gentio (MG)

Lapa Foice (MG)Lapa Varal (MG)

Boqueirão Soberbo (MG)GO-JA-01 (GO)MT-GU-01 (MT)

Abrigo Pilão (BA)Furna Estrago (PE)

Pedra Furada (PI)Sítio Meio (PI)

Caldeirão Rodrigues (PI)Toca Boa Vista I (PI)

Toca do Bojo (PI)Barra Antonião (PI)

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Archaeological Gaps in Rockshelters (Brazil)

Open-Air Sites: General Trends Open-Air Sites: General Trends for Central Brazil for Central Brazil If we take frequency of dates as a

proxy for intensity of human occupation, then

Dates for open-air sites seem to corroborate the pattern observed for rockshelters:

Two peaks, suggesting decrease in occupation during the mid-Holocene.

Frequency of dates for Central Frequency of dates for Central BrazilBrazil

Central States (MG-GO-BA-MT-MS)

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Open-Air Sites: General Trends Open-Air Sites: General Trends for Southern Brazilfor Southern BrazilNo evidence of “Archaic Gap” in

southern Brazil.Frequency of dates suggests stasis

in human population until about 2500 BP.

Steep increase in population after 2500 BP.

Southern States (SP-PR-SC-RS)

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What mean these patterns?What mean these patterns?

Main hypothesis: regional human abandonment linked to environmental conditions.

Climate, and specifically water availability, would be a plausible explanation.

Cross-checking with paleoenvironmental data is the next step.

Contrasting Paleoenvironmental Contrasting Paleoenvironmental and Archaeological Dataand Archaeological Data Analysis restricted to Central,

Southeastern and Southern Brazil. Northeastern and Northern Brazil were not

compared, either by insufficience of archaeological sources or insufficience of paleoenvironmental studies.

Coastal areas are not suitable, since most were under water.

Paleoenvironmental Data for Paleoenvironmental Data for Central BrazilCentral Brazil Overall, there is a good agreement between

archaeological and paleoenvironmental data:

frequency of charcoal in sediments, episodes of lake drought, pollen frequencies All pointing to mid-Holocene dry conditions

following a relatively moister early Holocene.

Paleonvironmental Data for Paleonvironmental Data for Southern Brazil (including SP) Southern Brazil (including SP) Also good correlation between

archaeological and paleoenvironmental data. Campos vegetation during most part of

Holocene suggests drier and cooler conditions. Perhaps low human density, with no population crashes.

Climatic ammelioration in the last 2,500 years coincides with steep increase in frequencies of archaeological dates.

Expanding the Model: The Expanding the Model: The Argentinian PampasArgentinian Pampas

Chosen because of excellent archaeological coverage.

Area subdivided into micro-environmental regions.

Abundance of paleoenvironmental studies.

Pampas: Main CharacteristicsPampas: Main Characteristics

Overall dry setting, with moist episodes.

Archaeological sites inside rockshelters show major chronological gaps.

Area Serrana Tandilia

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Area Interserrana

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Area Norte

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Subregion Pampa Seca

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Some Examples of Pampean Date Patterns in Different Regions

Pampas: Overall PatternPampas: Overall Pattern

Some areas unhabited due to sea-level changes.

Differences between regions probably due to migrations.

Are the patterns related to climate?

Pampean Dates x Paleosol FormationPampean Dates x Paleosol FormationPampas (Total)

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Pampean Paleosols

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Although the three-peaked pattern for archaeological dates and paleosol formation is the same, the”timing” is not.

Peaks of paleosol formation are more recent than the peaks of archaeological dates.

Probable explanation: paleosols were dated by means of total SOM, whereas archaeological dates are based on charcoal.

The total SOM dates are consistently more recent than charcoal dates, due to contamination by recent carbon.

This suggests that peaks of paleosol formation, related to increased moisture, are closely related to increase in human occupation.

Summary:Summary: Dryness periods and regional human

abandonment strongly correlated in Andean settings (Atacama,Chile).

Rockshelters in Central Brazil show signs of being abandoned by humans in the mid-Holocene.

Open-air sites in Central Brazil show a pattern of decreasing frequency in the mid-Holocene.

In the Pampas there is a good correlation between paleosol formation (wet periods) and frequency of archaeological dates.

Concluding: Holocene in South Concluding: Holocene in South AmericaAmerica Marked by dry periods. Humans had to cope with environmental

stress. Migration and territory abandonment were

widely used strategies. Archaeological sites (humans) are sensible

indicators of water stress, either directly or due to resources being exploited.