Overview
Jebel Irhoud
Fossils and Middle Stone Age artifacts from Jebel Irhoud occur in a context dated to about 315,000 years ago. The fossils combine modern-looking facial, mandibular, and dental traits with a more elongated, less globular braincase.
Evidence on this page
- Hublin et al. (2017), New fossils from Jebel Irhoud, Morocco and the pan-African origin of Homo sapiens
- Richter et al. (2017), The age of the hominin fossils from Jebel Irhoud, Morocco, and the origins of the Middle Stone Age
- Smith et al. (2007), Earliest evidence of modern human life history in North African early Homo sapiens
Important limits
- Bibliographic verification does not by itself establish that the full text was read.
- The evidence does not automatically support broader causal, technological, transmission, or literalizing claims beyond the cited record.
Current assessment
This assessment belongs to this record only. A connection never transfers evidence status from another topic.
Source foundation
4 public source records are linked to this topic. Source quantity does not replace source quality or methodological review.
- 2 Primary
- 2 Academic
4 academic-paper records · 0 with explicit free-full-text or open-access status
Evidence and claims
Recorded claims
Jebel Irhoud is consistent with a structured pan-African model of Homo sapiens emergence.
What the cited material supports
See linked sources and Source Synthesis.
Canonical sources cited
Jebel Irhoud is consistent with a structured pan-African model of Homo sapiens emergence.
PlausibleWhere the interpretations diverge
See Internet Folklore and Claim Mutation section.
What the cited evidence does not establish
Follow the claim source trail
This trail lists canonical source records attached to this item. Display order does not imply evidentiary rank or historical sequence.
- Hublin et al. (2017), New fossils from Jebel Irhoud, Morocco and the pan-African origin of Homo sapiens
Primary · verified
Bibliographic verification does not by itself establish that the full text was read.
- Scerri et al. (2018), Did Our Species Evolve in Subdivided Populations across Africa, and Why Does It Matter?
Academic · verified
Bibliographic verification does not by itself establish that the full text was read.
Jebel Irhoud preserves early Homo sapiens-clade fossils associated with a Middle Stone Age context dated to about 315,000 years ago.
What the cited material supports
Jebel Irhoud preserves a Middle Stone Age archaeological context and early Homo sapiens or Homo sapiens-clade fossils dating to roughly 315,000 years ago.
Canonical sources cited
Jebel Irhoud preserves early Homo sapiens-clade fossils associated with a Middle Stone Age context dated to about 315,000 years ago.
Well supportedWhere the interpretations diverge
See Internet Folklore and Claim Mutation section.
What the cited evidence does not establish
Follow the claim source trail
This trail lists canonical source records attached to this item. Display order does not imply evidentiary rank or historical sequence.
- Hublin et al. (2017), New fossils from Jebel Irhoud, Morocco and the pan-African origin of Homo sapiens
Primary · verified
Bibliographic verification does not by itself establish that the full text was read.
- Richter et al. (2017), The age of the hominin fossils from Jebel Irhoud, Morocco, and the origins of the Middle Stone Age
Primary · verified
Bibliographic verification does not by itself establish that the full text was read.
The fossils’ mosaic anatomy leaves room for debate over how broadly early Homo sapiens should be defined relative to late archaic African Homo.
What the cited material supports
The fossils' mosaic anatomy leaves room for debate over how broadly early Homo sapiens should be defined relative to late archaic African Homo.
Canonical sources cited
The fossils’ mosaic anatomy leaves room for debate over how broadly early Homo sapiens should be defined relative to late archaic African Homo.
Active debateWhere the interpretations diverge
See Internet Folklore and Claim Mutation section.
What the cited evidence does not establish
Follow the claim source trail
This trail lists canonical source records attached to this item. Display order does not imply evidentiary rank or historical sequence.
- Hublin et al. (2017), New fossils from Jebel Irhoud, Morocco and the pan-African origin of Homo sapiens
Primary · verified
Bibliographic verification does not by itself establish that the full text was read.
Jebel Irhoud alone cannot establish exact ancestry pathways among early African Homo sapiens populations.
What the cited material supports
A pan-African emergence model fits the distributed fossil record, but the exact population network and ancestry pathways cannot be read from this site alone.
Canonical sources cited
Jebel Irhoud alone cannot establish exact ancestry pathways among early African Homo sapiens populations.
UncertainWhere the interpretations diverge
See Internet Folklore and Claim Mutation section.
What the cited evidence does not establish
Follow the claim source trail
This trail lists canonical source records attached to this item. Display order does not imply evidentiary rank or historical sequence.
- Hublin et al. (2017), New fossils from Jebel Irhoud, Morocco and the pan-African origin of Homo sapiens
Primary · verified
Bibliographic verification does not by itself establish that the full text was read.
- Scerri et al. (2018), Did Our Species Evolve in Subdivided Populations across Africa, and Why Does It Matter?
Academic · verified
Bibliographic verification does not by itself establish that the full text was read.
Jebel Irhoud does not establish Morocco as the sole birthplace of Homo sapiens.
What the cited material supports
The site does not establish a Morocco-only birthplace, ancient intervention, or a lost advanced civilization.
Canonical sources cited
Jebel Irhoud does not establish Morocco as the sole birthplace of Homo sapiens.
Well supportedWhere the interpretations diverge
See Internet Folklore and Claim Mutation section.
What the cited evidence does not establish
Follow the claim source trail
This trail lists canonical source records attached to this item. Display order does not imply evidentiary rank or historical sequence.
- Hublin et al. (2017), New fossils from Jebel Irhoud, Morocco and the pan-African origin of Homo sapiens
Primary · verified
Bibliographic verification does not by itself establish that the full text was read.
- Scerri et al. (2018), Did Our Species Evolve in Subdivided Populations across Africa, and Why Does It Matter?
Academic · verified
Bibliographic verification does not by itself establish that the full text was read.
Evidence Ledger
Hublin et al
Hublin et al. (2017), New fossils from Jebel Irhoud, Morocco and the pan-African origin of Homo sapiens
What this supports
- Jebel Irhoud is consistent with a structured pan-African model of Homo sapiens emergence.
- Jebel Irhoud preserves early Homo sapiens-clade fossils associated with a Middle Stone Age context dated to about 315,000 years ago.
- The fossils’ mosaic anatomy leaves room for debate over how broadly early Homo sapiens should be defined relative to late archaic African Homo.
- Jebel Irhoud alone cannot establish exact ancestry pathways among early African Homo sapiens populations.
- Jebel Irhoud does not establish Morocco as the sole birthplace of Homo sapiens.
What this does not establish
Bibliographic verification does not by itself establish that the full text was read.
Follow the Source
This trail lists canonical source records attached to this item. Display order does not imply evidentiary rank or historical sequence.
- Hublin et al. (2017), New fossils from Jebel Irhoud, Morocco and the pan-African origin of Homo sapiens
Primary · verified
Bibliographic verification does not by itself establish that the full text was read.
Richter et al
Richter et al. (2017), The age of the hominin fossils from Jebel Irhoud, Morocco, and the origins of the Middle Stone Age
What this supports
- Jebel Irhoud preserves early Homo sapiens-clade fossils associated with a Middle Stone Age context dated to about 315,000 years ago.
What this does not establish
Bibliographic verification does not by itself establish that the full text was read.
Follow the Source
This trail lists canonical source records attached to this item. Display order does not imply evidentiary rank or historical sequence.
- Richter et al. (2017), The age of the hominin fossils from Jebel Irhoud, Morocco, and the origins of the Middle Stone Age
Primary · verified
Bibliographic verification does not by itself establish that the full text was read.
Smith et al
Smith et al. (2007), Earliest evidence of modern human life history in North African early Homo sapiens
What this supports
No direct public claim-support relationship is recorded for this evidence item.
What this does not establish
Bibliographic verification does not by itself establish that the full text was read.
Follow the Source
This trail lists canonical source records attached to this item. Display order does not imply evidentiary rank or historical sequence.
- Smith et al. (2007), Earliest evidence of modern human life history in North African early Homo sapiens
Academic · verified
Bibliographic verification does not by itself establish that the full text was read.
Scerri et al
Scerri et al. (2018), Did Our Species Evolve in Subdivided Populations across Africa, and Why Does It Matter?
What this supports
- Jebel Irhoud is consistent with a structured pan-African model of Homo sapiens emergence.
- Jebel Irhoud alone cannot establish exact ancestry pathways among early African Homo sapiens populations.
- Jebel Irhoud does not establish Morocco as the sole birthplace of Homo sapiens.
What this does not establish
Bibliographic verification does not by itself establish that the full text was read.
Follow the Source
This trail lists canonical source records attached to this item. Display order does not imply evidentiary rank or historical sequence.
- Scerri et al. (2018), Did Our Species Evolve in Subdivided Populations across Africa, and Why Does It Matter?
Academic · verified
Bibliographic verification does not by itself establish that the full text was read.
View as Evidence Matrix
Each row remains a separate evidence record. One proxy or finding does not automatically determine the assessment of an entire compound claim.
| ID | Evidence | Supports | Challenges | Main limitation | Sources |
|---|---|---|---|---|---|
| CM-006-EV-001 | Hublin et al. (2017), New fossils from Jebel Irhoud, Morocco and the pan-African origin of Homo sapiens | Jebel Irhoud is consistent with a structured pan-African model of Homo sapiens emergence.; Jebel Irhoud preserves early Homo sapiens-clade fossils associated with a Middle Stone Age context dated to about 315,000 years ago.; The fossils’ mosaic anatomy leaves room for debate over how broadly early Homo sapiens should be defined relative to late archaic African Homo.; Jebel Irhoud alone cannot establish exact ancestry pathways among early African Homo sapiens populations.; Jebel Irhoud does not establish Morocco as the sole birthplace of Homo sapiens. | No direct public challenge relationship recorded | Bibliographic verification does not by itself establish that the full text was read. | 1 |
| CM-006-EV-002 | Richter et al. (2017), The age of the hominin fossils from Jebel Irhoud, Morocco, and the origins of the Middle Stone Age | Jebel Irhoud preserves early Homo sapiens-clade fossils associated with a Middle Stone Age context dated to about 315,000 years ago. | No direct public challenge relationship recorded | Bibliographic verification does not by itself establish that the full text was read. | 1 |
| CM-006-EV-003 | Smith et al. (2007), Earliest evidence of modern human life history in North African early Homo sapiens | No direct public support relationship recorded | No direct public challenge relationship recorded | Bibliographic verification does not by itself establish that the full text was read. | 1 |
| CM-006-EV-004 | Scerri et al. (2018), Did Our Species Evolve in Subdivided Populations across Africa, and Why Does It Matter? | Jebel Irhoud is consistent with a structured pan-African model of Homo sapiens emergence.; Jebel Irhoud alone cannot establish exact ancestry pathways among early African Homo sapiens populations.; Jebel Irhoud does not establish Morocco as the sole birthplace of Homo sapiens. | No direct public challenge relationship recorded | Bibliographic verification does not by itself establish that the full text was read. | 1 |
Timeline
~315,000 BCE
Approximate ordering never replaces this visible date basis.
| Date / period | Event | Why it matters | |---|---|---| | Middle Pleistocene | Early Homo sapiens populations exist across parts of Africa | Broad context for Jebel Irhoud, Omo Kibish, Herto, Florisbad, and related debates | | About 315,000 +/- 34,000 years ago | Main Jebel Irhoud fossil-bearing context dated by thermoluminescence on burned flints | Places early Homo sapiens in North Africa much earlier than older simplified timelines | | 1961 | A cranium is discovered during mining activity at Jebel Irhoud | Begins the modern fossil history of the site | | 1962 | Emile Ennouchi publishes early descriptions and interprets the fossil in a Neanderthal-like framework | Shows how interpretation changed with better methods and comparison samples | | 1967 and 1969 | Additional excavations recover later fossils | Adds Irhoud 4 and 5 and improves the fossil inventory | | 1980s to 1990s | Reassessment increasingly reconsiders the fossils as archaic Homo sapiens or early Homo sapiens rather than Neanderthal | Moves the site into modern human origins debates | | 2004 onward | New excavations led by Hublin and Ben-Ncer recover more fossils and controlled archaeological context | Creates the foundation for the 2017 reassessment | | 2007 | Smith et al.
Approximate ordering never replaces this visible date basis.
Local Atlas Map
Accessible local relationship list
Jebel Irhoud → Forbidden Archaeology
Inspect connection as text
What this does not prove
One accepted revision illustrates evidentiary method; it does not by itself adjudicate every anomaly cited by Cremo and Thompson.
Supporting sources: Cremo and Thompson (1993), Forbidden Archeology: The Hidden History of the Human Race, Richter et al. (2017), The age of the hominin fossils from Jebel Irhoud, Morocco, and the origins of the Middle Stone Age
Jebel Irhoud → Out of Africa Theory
Inspect connection as text
What this does not prove
Jebel Irhoud supports African origin but does not prove a Morocco-only origin, a single migration route, or exact later ancestry.
Supporting sources: Hublin et al. (2017), New fossils from Jebel Irhoud, Morocco and the pan-African origin of Homo sapiens, Scerri et al. (2018), Did Our Species Evolve in Subdivided Populations across Africa, and Why Does It Matter?
Jebel Irhoud → Human Origins
Inspect connection as text
What this does not prove
This edge concerns biological and archaeological origins evidence, not religious, mythic, or cultural meaning.
Supporting sources: Hublin et al. (2017), New fossils from Jebel Irhoud, Morocco and the pan-African origin of Homo sapiens, Richter et al. (2017), The age of the hominin fossils from Jebel Irhoud, Morocco, and the origins of the Middle Stone Age
Jebel Irhoud → Out of Africa Theory
Inspect connection as text
What this does not prove
The site broadens the African map; it does not establish Morocco as the sole origin or trace a direct ancestry path to all living humans.
Supporting sources: Hublin et al. (2017), New fossils from Jebel Irhoud, Bergström et al. (2021), Origins of modern human ancestry
Jebel Irhoud → Human Origins
Inspect connection as text
What this does not prove
The Jebel Irhoud evidence is an early Homo sapiens anchor; it does not by itself establish one isolated birthplace or direct ancestry for every later population.
Supporting sources: New fossils from Jebel Irhoud, Morocco and the pan-African origin of Homo sapiens, The age of the hominin fossils from Jebel Irhoud, Morocco, and the origins of the Middle Stone Age
Jebel Irhoud → Hominin Evolution
Inspect connection as text
What this does not prove
The site is one evidence node; it does not identify a sole birthplace or a direct ancestor-descendant chain for later populations.
Supporting sources: Hublin et al. (2017), New fossils from Jebel Irhoud, Morocco and the pan-African origin of Homo sapiens, Richter et al. (2017), The age of the hominin fossils from Jebel Irhoud, Morocco, and the origins of the Middle Stone Age
Jebel Irhoud → Ancient DNA
Inspect connection as text
What this does not prove
This is a methodological contrast, not molecular evidence from Jebel Irhoud; absence of a cited genome does not invalidate the fossil record.
Supporting sources: Hublin et al. (2017), New fossils from Jebel Irhoud, Morocco and the pan-African origin of Homo sapiens, Richter et al. (2017), The age of the hominin fossils from Jebel Irhoud, Morocco, and the origins of the Middle Stone Age
Jebel Irhoud → Ancient Pre-Human Civilization Theory
Inspect connection as text
What this does not prove
This is corrective comparison only: the sources do not document the pre-human-civilization claim’s diffusion and do not test every hypothetical deep-time civilization scenario.
Supporting sources: Hublin et al. (2017), New fossils from Jebel Irhoud, Morocco and the pan-African origin of Homo sapiens, Richter et al. (2017), The age of the hominin fossils from Jebel Irhoud, Morocco, and the origins of the Middle Stone Age
Documented connections
Jebel Irhoud → Forbidden Archaeology
Inspect connection as text
What this does not prove
One accepted revision illustrates evidentiary method; it does not by itself adjudicate every anomaly cited by Cremo and Thompson.
Supporting sources: Cremo and Thompson (1993), Forbidden Archeology: The Hidden History of the Human Race, Richter et al. (2017), The age of the hominin fossils from Jebel Irhoud, Morocco, and the origins of the Middle Stone Age
Jebel Irhoud → Out of Africa Theory
Inspect connection as text
What this does not prove
Jebel Irhoud supports African origin but does not prove a Morocco-only origin, a single migration route, or exact later ancestry.
Supporting sources: Hublin et al. (2017), New fossils from Jebel Irhoud, Morocco and the pan-African origin of Homo sapiens, Scerri et al. (2018), Did Our Species Evolve in Subdivided Populations across Africa, and Why Does It Matter?
Jebel Irhoud → Human Origins
Inspect connection as text
What this does not prove
This edge concerns biological and archaeological origins evidence, not religious, mythic, or cultural meaning.
Supporting sources: Hublin et al. (2017), New fossils from Jebel Irhoud, Morocco and the pan-African origin of Homo sapiens, Richter et al. (2017), The age of the hominin fossils from Jebel Irhoud, Morocco, and the origins of the Middle Stone Age
Jebel Irhoud → Out of Africa Theory
Inspect connection as text
What this does not prove
The site broadens the African map; it does not establish Morocco as the sole origin or trace a direct ancestry path to all living humans.
Supporting sources: Hublin et al. (2017), New fossils from Jebel Irhoud, Bergström et al. (2021), Origins of modern human ancestry
Jebel Irhoud → Human Origins
Inspect connection as text
What this does not prove
The Jebel Irhoud evidence is an early Homo sapiens anchor; it does not by itself establish one isolated birthplace or direct ancestry for every later population.
Supporting sources: New fossils from Jebel Irhoud, Morocco and the pan-African origin of Homo sapiens, The age of the hominin fossils from Jebel Irhoud, Morocco, and the origins of the Middle Stone Age
Jebel Irhoud → Hominin Evolution
Inspect connection as text
What this does not prove
The site is one evidence node; it does not identify a sole birthplace or a direct ancestor-descendant chain for later populations.
Supporting sources: Hublin et al. (2017), New fossils from Jebel Irhoud, Morocco and the pan-African origin of Homo sapiens, Richter et al. (2017), The age of the hominin fossils from Jebel Irhoud, Morocco, and the origins of the Middle Stone Age
Jebel Irhoud → Ancient DNA
Inspect connection as text
What this does not prove
This is a methodological contrast, not molecular evidence from Jebel Irhoud; absence of a cited genome does not invalidate the fossil record.
Supporting sources: Hublin et al. (2017), New fossils from Jebel Irhoud, Morocco and the pan-African origin of Homo sapiens, Richter et al. (2017), The age of the hominin fossils from Jebel Irhoud, Morocco, and the origins of the Middle Stone Age
Jebel Irhoud → Ancient Pre-Human Civilization Theory
Inspect connection as text
What this does not prove
This is corrective comparison only: the sources do not document the pre-human-civilization claim’s diffusion and do not test every hypothetical deep-time civilization scenario.
Supporting sources: Hublin et al. (2017), New fossils from Jebel Irhoud, Morocco and the pan-African origin of Homo sapiens, Richter et al. (2017), The age of the hominin fossils from Jebel Irhoud, Morocco, and the origins of the Middle Stone Age
Sources
Academic papers
4 paper citations support or limit this topic; 0 carry explicit free-full-text or open-access status.
Academic
Smith et al. (2007), Earliest evidence of modern human life history in North African early Homo sapiens
Why Ancient Inquiry uses this source
Synchrotron-based dental development study of the Irhoud 3 juvenile
What it does not establish
Bibliographic verification does not by itself establish that the full text was read.
Scerri et al. (2018), Did Our Species Evolve in Subdivided Populations across Africa, and Why Does It Matter?
Why Ancient Inquiry uses this source
Scholarly synthesis supporting a structured pan-African model
What it does not establish
Bibliographic verification does not by itself establish that the full text was read.
Primary
Hublin et al. (2017), New fossils from Jebel Irhoud, Morocco and the pan-African origin of Homo sapiens
Why Ancient Inquiry uses this source
Primary fossil description, reconstruction, comparative morphology, and taxonomic interpretation
What it does not establish
Bibliographic verification does not by itself establish that the full text was read.
Richter et al. (2017), The age of the hominin fossils from Jebel Irhoud, Morocco, and the origins of the Middle Stone Age
Why Ancient Inquiry uses this source
Primary thermoluminescence chronology and supporting US-ESR recalculation
What it does not establish
Bibliographic verification does not by itself establish that the full text was read.
Research detail
Topic ID: CM-006 Last reviewed: 2026-08-10 Corrections: /corrections/ Change history: Recorded in the Connected Atlas topic changelog.
Overview
Fossils and Middle Stone Age artifacts from Jebel Irhoud occur in a context dated to about 315,000 years ago. The fossils combine modern-looking facial, mandibular, and dental traits with a more elongated, less globular braincase.
Plain-language explanation
Jebel Irhoud preserves very early members of the Homo sapiens clade in Morocco. The evidence supports an early North African population, not the first individual human or a Morocco-only birthplace for humanity.
Historical and scholarly context
What the site changed
Jebel Irhoud changed the timeline and geography of early Homo sapiens discussions. The 2017 studies did not simply add an older date. They tied human fossils, Middle Stone Age tools, stratigraphy, and dating evidence together in a North African context. This made it harder to describe modern human origins as a quick, localized event in one small part of East Africa.
Why the fossils are described as a mosaic
The fossils combine traits that do not fit a clean "archaic versus modern" split. The face, mandible, and teeth align more closely with early or recent modern humans. The braincase is more primitive in shape, especially compared with the rounded skull shape typical of recent Homo sapiens. This supports a gradual model in which some human traits became established before others.
Why the date matters
Richter and colleagues did not directly date the fossils with radiocarbon, which is not useful at this age range. Instead, they dated fire-heated flint artifacts from the same Middle Stone Age context using thermoluminescence and compared the result with a recalculated uranium-series/electron spin resonance date on a tooth from Irhoud 3 mandible. The key date is a weighted average of 315,000 +/- 34,000 years ago for the artifacts and associated fossil context.
Why this does not erase East Africa
East Africa remains critical to human origins. Omo Kibish, Herto, and other eastern African sites still matter. Jebel Irhoud widens the map. It shows that North Africa also preserves early Homo sapiens evidence around the time when our species was emerging.
What the evidence supports
- The 2017 Nature fossil study identifies a coherent anatomical pattern: modern-like face, jaw, and teeth combined with a more archaic braincase.
- The 2017 Nature dating study anchors the fossil-bearing context to about 315,000 +/- 34,000 years through thermoluminescence dating of burned flints, supported by recalculated US-ESR dating.
- The fossils and tools come from a Middle Stone Age context, fitting the broader African timing of early Homo sapiens emergence and Middle Stone Age technological expansion.
- Later pan-African models explain why early Homo sapiens evidence appears across different parts of Africa rather than only one narrow region.
Limits and disputed claims
- No ancient DNA: There is no published genome from Jebel Irhoud. Genetic claims about this population should be treated cautiously.
- Not a precise "first human" date: The 315,000 year age estimate is strong for the site context, but it is not a claim that the first Homo sapiens individual was born there at exactly that date.
- Taxonomic boundary issue: Some disagreement comes from how researchers define early Homo sapiens versus late archaic Homo in Africa. The fossils are best presented as early members of the Homo sapiens clade or early Homo sapiens, not "fully modern people."
- Headline compression: Media often turns "oldest reported Homo sapiens fossils" into "first man." That loses the evolutionary and population-level nature of the evidence.
- Fringe overreach: No artifact, tool, fossil, or dating evidence at Jebel Irhoud supports ancient astronaut intervention, lost civilization, or suppressed advanced technology claims.
Claim status
- Plausible: Jebel Irhoud is consistent with a structured pan-African model of Homo sapiens emergence.
- Well supported: Jebel Irhoud preserves early Homo sapiens-clade fossils associated with a Middle Stone Age context dated to about 315,000 years ago.
- Active debate: The fossils’ mosaic anatomy leaves room for debate over how broadly early Homo sapiens should be defined relative to late archaic African Homo.
- Uncertain: Jebel Irhoud alone cannot establish exact ancestry pathways among early African Homo sapiens populations.
- Well supported: Jebel Irhoud does not establish Morocco as the sole birthplace of Homo sapiens.
Sources
- Hublin et al. (2017), New fossils from Jebel Irhoud, Morocco and the pan-African origin of Homo sapiens — https://doi.org/10.1038/nature22336
- Richter et al. (2017), The age of the hominin fossils from Jebel Irhoud, Morocco, and the origins of the Middle Stone Age — https://doi.org/10.1038/nature22335
- Smith et al. (2007), Earliest evidence of modern human life history in North African early Homo sapiens — https://doi.org/10.1073/pnas.0700747104
- Scerri et al. (2018), Did Our Species Evolve in Subdivided Populations across Africa, and Why Does It Matter? — https://doi.org/10.1016/j.tree.2018.05.005
This public draft omits internal numeric scoring and administrative notes. Claim labels describe evidentiary status, not topic importance.