Abstract Archaeological and geological remains associated with the Youngest Toba Tuff (YTT) deposits in India are seen as significant proxies for reconstructing (1) initial modern human colonization of India and (2) possible climatic impacts of the Toba super-eruption of 74 ka on the Indian climate and hominin behaviour. In order to gain further insights into the environmental impacts and behavioural adaptations of human populations in India before and after the Toba eruption, we investigated archaeological horizons associated with the Toba ash beds along the Gundlakamma basin in Prakasam District, Andhra Pradesh, India. Here, lithic artefacts were identified below and above the YTT deposits. The YTT deposits in the Gundlakamma River basin have a maximum thickness of 50 cm, comparatively thinner than those at the better investigated valleys of the adjacent Jurreru and Sagileru in Andhra Pradesh and the Son, Madhya Pradesh, India. Our surveys indicate that the Palaeolithic assemblages associated with YTT deposits from the Gundlakamma River basin can provide significant insights into the issues and debates surrounding the Toba archaeology.

Abstract Progress over the last 20 years in establishing reliable benchmarks in the Paleolithic of India has been uneven but major successes have been the dating of the earliest Acheulean assemblages in India; the dating of the onset of the Middle Stone Age; the dating of the earliest microlithic assemblages in India; and the dating of the antiquity of human occupation of rain forests in South India and Sri Lanka. Also important is our greater understanding of the Younger Toba Tuff and the impact of the Toba megaeruption 74 ka ago on hominin populations in India. Major uncertainties persist over when the genus Homo first entered South Asia; when our own species, H. sapiens first entered South Asia; the age of the earliest blade assemblages in India; and the antiquity of its rock art.

Volcanic features are common on geologically active earthlike planets. Megascale or “super” eruptions involving >1000 Gt of magma have occurred on both Earth and Mars in the geologically recent past, introducing prodigious volumes of ash and volcanic gases into the atmosphere. Here we discuss felsic (explosive) and mafic (flood lava) supereruptions and their potential atmospheric and environmental effects on both planets. On Earth, felsic supereruptions recur on average about every 100–200,000 years and our present knowledge of the 73.5 ka Toba eruption implies that such events can have the potential to be catastrophic to human civilization. A future eruption of this type may require an unprecedented response from humankind to assure the continuation of civilization as we know it. Mafic supereruptions have resulted in atmospheric injection of volcanic gases (especially SO 2 ) and may have played a part in punctuating the history of life on Earth. The contrast between the more sustained effects of flood basalt eruptions (decades to centuries) and the near-instantaneous effects of large impacts (months to years) is worthy of more detailed study than has been completed to date. Products of mafic supereruptions, significantly larger than known from the geologic record on Earth, are well preserved on Mars. The volatile emissions from these eruptions most likely had global dispersal, but the effects may not have been outside what Mars endures even in the absence of volcanic eruptions. This is testament to the extreme variability of the current Martian atmosphere: situations that would be considered catastrophic on Earth are the norm on Mars.